Middle Assyrian Empire

The Middle Assyrian Empire was founded through Assur, a city-state through most of the preceding Old Assyrian period, and the surrounding territories achieving independence from the Mitanni kingdom. Under Ashur-uballit, Assyria began to expand and assert its place as one of the great powers of the Ancient Near East. This aspiration chiefly came into fruition through the efforts of the kings Adad-nirari I (r. c. 1305–1274 BC), Shalmaneser I (r. c. 1273–1244 BC) and Tukulti-Ninurta I (r. c. 1243–1207 BC), under whom Assyria expanded to for a time become the dominant power in Mesopotamia. The reign of Tukulti-Ninurta I marked the height of the Middle Assyrian Empire and included the subjugation of Babylonia and the foundation of a new capital city, Kar-Tukulti-Ninurta, though it was abandoned after his death. Though Assyria was left largely unscathed by the direct effects of the Late Bronze Age collapse of the 12th century BC, the Middle Assyrian Empire began to experience a significant period of decline roughly at the same time. The assassination of Tukulti-Ninurta I c. 1207 BC led to inter-dynastic conflict and a significant decline in Assyrian power.

Even during its period of decline, Middle Assyrian kings continued to be assertive geopolitically; both Ashur-dan I (r. c. 1178–1133 BC) and Ashur-resh-ishi I (r. 1132–1115 BC) campaigned against Babylonia. Under Ashur-resh-ishi I's son and successor Tiglath-Pileser I (r. 1114–1076 BC), the Middle Assyrian Empire experienced a period of resurgence, owing to wide-ranging campaigns and conquests. Tiglath-Pileser's armies marched as far from the Assyrian heartland as the Mediterranean. Though the reconquered and newly conquered lands were held on to for some time, the empire experienced a second and more catastrophic period of decline after the death of Tiglath-Pileser's son Ashur-bel-kala (r. 1073–1056 BC), which saw the loss of most of the empire's territories outside of its heartlands, partly due to invasions by Aramean tribes. Assyrian decline began to be reversed again under Ashur-dan II (r. 934–912 BC), who campaigned extensively in the peripheral regions of the Assyrian heartland. The successes of Ashur-dan II and his immediate successors in restoring Assyrian rule over the empire's former lands, and in time going far beyond them, is used by modern historians to mark the transition from the Middle Assyrian Empire to the succeeding Neo-Assyrian Empire.

Theologically, the Middle Assyrian period saw important transformations of the role of Ashur. Having originated as a deified personification of the city of Assur itself sometime centuries earlier in the Early Assyrian period, Ashur in the Middle Assyrian period became equated with the old Sumerian head of the pantheon, Enlil, and was as a result of Assyrian expansionism and warfare transformed from a primarily agricultural god into a military one. The transition of Assyria from a city-state into an empire also had important administrative and political consequences. While the Assyrian rulers of the Old Assyrian period had governed with the title iššiak ("governor") jointly with a city assembly made up of influential figures from Assur, the Middle Assyrian kings were autocratic rulers who used the title šar ("king") and sought equal status to the monarchs of other empires. The transition into an empire also led to the development of various necessary systems, such as a sophisticated road system, various administrative divisions of territory and a complex web of royal administrators and officials.

History

Formation and rise

Assyria became an independent territorial state under Ashur-uballit I c. 1363 BC, having previously been under the suzerainty of the Mitanni kingdom. Though the transition of Assyria from being merely a city-state around Assur (as it was throughout most of the preceding Old Assyrian period) had begun already in the last few decades under Mittani suzerainty, it is the independence achieved under Ashur-uballit, as well as Ashur-uballit's conquests of nearby territories, such as the fertile region between the Tigris, the foothills of the Taurus Mountains and the Upper Zab, which modern historians use to mark the beginning of the Middle Assyrian period.

Ashur-uballit was the first native Assyrian ruler to claim the royal title šar ("king"), and the first ruler of Assur to do so since the time of the Amorite conqueror Shamshi-Adad I in the 18th century BC. Shortly after achieving independence, he further claimed the dignity of a great king on the level of the pharaohs and the Hittite kings. Ashur-uballit's claim to be a great king meant that he also embedded himself in the ideological implications of that role; a great king was expected to expand the borders of his realm to incorporate "uncivilized" territories, ideally eventually ruling the entire world. On account of political realism however, the true situation was most often diplomacy with adversaries of equal rank, such as Babylonia, and conquest only of smaller and military inferior states in the near vicinity. Ashur-uballit's reign was often regarded by later generations of Assyrians as the true birth of Assyria. The term "land of Ashur" (māt Aššur), i.e. designating Assyria as comprising a larger kingdom, is first attested as being used in his time.

The rise of Assyria was intertwined with the decline and collapse of its former suzerain, Mitanni. Assyria was subjugated by Mittani c. 1430 BC, and as such spent about 70 years under Mitanni rule. Chiefly responsible for bringing an end to Mitanni dominance in northern Mesopotamia was the Hittite king Šuppiluliuma I, whose 14th century BC war with Mitanni over control of Syria effectively led to the beginning of the end of the Mitanni kingdom. It was in this struggle for supremacy and hegemony that Ashur-uballit secured independence. The Mittani-Hittite conflict was preceded by a period of weakness in the Mitanni kingdom; the heir to the Mitanni throne, Artashumara, was murdered in the 14th century BC, which led to the accession of the otherwise minor figure Tushratta. Tushratta's rise to power led to internal conflict within the Mittani kingdom as different factions vied with each other to depose him. During the wars that followed Tushratta's accession, multiple rivals came to rule Mitanni, such as Artatama II and Shuttarna III. The Assyrians sometimes fought them and sometimes allied with them. Shuttarna III secured Assyrian support, but had to pay heavily for it in silver and gold.

Ashur-uballit, doubtlessly watching the conflict between Mitanni and the Hittites closely out of interest in expanding Assyria, directed much of his attention to the lands south of his realm. Successful campaigns were directed against both Arrapha and Nuzi, which was destroyed by Assyrian troops in the 1330s BC or before. Neither city was formally incorporated into Assyria; the Assyrian army probably withdrew to the Little Zab, allowing Babylonia to conquer the sites. In the centuries to come, Assyrian kings often found themselves as rivals of the Babylonian kings. Ashur-uballit himself did not wish to engage in long-lasting conflicts with the Babylonians, clearly illustrated since he married his daughter Muballitat-Serua to the Babylonian king Burnaburiash II. Prior to achieving peace, Burnaburiash had been a prominent enemy of the Assyrians. At one point, he had attempted to tarnish Assyrian diplomatic and trade relations with Egypt by sending a letter to the pharaoh Akhenaten wherein he falsely claimed that the Assyrians were his vassals. After several years of peaceful co-existence between Assyria and Babylonia, the Babylonian king Kara-hardash, son of Burnaburiash and Muballitat-Serua, was overthrown. Muballitat-Serua was most likely killed at the same time, which prompted Ashur-uballit to march south and restore order. The usurper who had taken Babylonia in the meantime, Nazi-Bugash, was overthrown and replaced by the Assyrians with Kurigalzu II, another son of Burnaburiash.

Ashur-uballit's successors Enlil-nirari (r. c. 1327–1318 BC) and Arik-den-ili (r. c. 1317–1306 BC) were less successful than Ashur-uballit in expanding and consolidating Assyrian power, and as such the new kingdom developed somewhat haltingly and remained fragile. Kurigalzu did not remain loyal to the Assyrians and instead fought with Enlil-nirari. His treason and betrayal resulted in deep trauma, still referenced in Assyrian writings concerning diplomacy and wars against Babylonia more than a century later; it was seen by many later Assyrians as the starting point of the historical enmity between the two civilizations. At one point, Kurigalzu reached as far into the Assyrian lands as Sugagu, a settlement located only a day's journey from Assur. Although the Assyrians drove him away, an incursion this deep into the Assyrian heartland left an impression on the Assyrians, who in future conflicts often focused on Babylonian border outposts along the eastern Tigris river as a preventive measure.

First period of expansion and consolidation

Reigns of Adad-nirari I and Shalmaneser I

Under the warrior-kings Adad-nirari I (r. c. 1305–1274 BC), Shalmaneser I (r. c. 1273–1244 BC) and Tukulti-Ninurta I (r. c. 1243–1207 BC), Assyria began to realize its aspirations of becoming a significant regional power. Though the other powers of the Ancient Near East, such as Egypt, the Hittites and Babylonia, had at first been reluctant to view the new Assyrian kingdom as their equal, from the time of Adad-nirari I onwards, when Assyria grew to take the place of Mitanni, its status as one of the major kingdoms became undeniable. Adad-nirari I was the first Assyrian king to march against the remnants of the Mitanni kingdom and the first Assyrian king to include lengthy narratives of his campaigns in his royal inscriptions. Adad-nirari early in his reign defeated Shattuara I of Mitanni and forced him to pay tribute to Assyria as a vassal ruler. Given that the Assyrian army extensively plundered and destroyed portions of Mitanni during this campaign, it is unlikely that there at this point were any plans to outright annex and consolidate the Mitanni lands. Sometime later, Shattuara's son Wasashatta rebelled against the Assyrians, though was defeated by Adad-nirari who, as punishment, annexed several cities alongside the Khabur river. At Taite, a former Mitanni capital, Adad-nirari constructed a royal palace for himself.

The primary focus of Adad-nirari was the conquest and/or pacification of Babylonia. Not only did Babylonia present a more immediate threat, but conquering southern Mesopotamia would also be more prestigious. Through military focus on Babylonian border towns, such as Lubdi and Rapiqu, it is clear that Adad-nirari's ultimate goal was to subdue the Babylonians and achieve hegemony over all of Mesopotamia. Adad-nirari's temporary occupations of Lubdi and Rapiqu were met with an attack by the Babylonian king Nazi-Maruttash, though Adad-nirari defeated him at the Battle of Kār Ištar c. 1280 BC and the Assyro-Babylonian border was redrawn in Assyria's favor. Under Adad-nirari's son Shalmaneser I, Assyrian campaigns against its neighbors and equals intensified. According to his own inscriptions, Shalmaneser conquered eight countries (likely minor states) in the first year of his reign. Among the sites captured was the fortress Arinnu, which Shalmaneser razed to the ground and turned into dust. Some of the dust from Arinnu was collected and symbolically brought back to Assur.

After the new Mitanni king Shattuara II rebelled against Assyrian authority, assisted by the Hittites, further campaigns were conducted against Mitanni in order to suppress the resistance. Shalmaneser's campaign against Mitanni was a great success; the Mitanni capital of Washukanni was sacked and, realizing that the Mitanni lands were clearly not controllable through allowing the local rulers to continue to govern as vassals, the kingdom's lands were with some reluctance annexed into the Assyrian kingdom. The lands were not annexed directly into the royal domains, but rather placed under the rule of a viceroy who bore the title of grand vizier and king of Hanigalbat. The first such ruler was Shalmaneser's brother, Ibashi-ili, whose descendants later continued to occupy the position. This arrangement, placing the Mitanni lands under the rule of a lesser branch of the royal family, suggests that the Assyrian elites in the heartland had only a marginal interest in the new conquests. Though Shalmaneser boasted of brutal acts against the defeated Mitanni armies, in one inscription claiming to have blinded over 14,000 prisoners of war, he was also one of the first Assyrian kings to take prisoners in the first place instead of simply executing captured enemies. Adad-nirari was also a great builder; among his most significant construction projects was the construction of the city of Nimrud, a highly significant site in later Assyrian history.

Under Shalmaneser, the Assyrians also conducted significant campaigns against the Hittites. Already in the time of Adad-nirari, Assyrian envoys had been treated poorly at the court of the Hittite king Mursili III. When Mursili's successor Hattusili III reached out to Shalmaneser in an attempt to forge an alliance, probably due to recent losses against Egypt, he was insultingly rejected and called a "substitute of a great king". The strained relations between the two empires sometimes erupted into war; Shalmaneser warred several times against Hittite vassal states in the Levant. The hostilities reached their zenith under Shalmaneser's son and successor Tukulti-Ninurta I, who defeated the Hittites at the Battle of Nihriya c. 1237 BC. The Hittite defeat at Nihriya marked the beginning of the end of their influence in northern Mesopotamia.

Reign of Tukulti-Ninurta I

Shalmaneser I's son Tukulti-Ninurta I became king c. 1243 BC. He had, according to historian Stefan Jakob, "an unconditional will to create something that would last forever" and his wide-ranging conquests brought the Middle Assyrian Empire to its greatest extent. Even before he became king, neighboring kingdoms had been wary of his accession; when he assumed the throne, the Hittite king Tudḫaliya IV sent him a letter of congratulations but secretly also sent a letter to the Assyrian grand vizier Babu-aha-iddina in which he implored the vizier to dissuade Tukulti-Ninurta from attacking the Hittite territories in the mountains northwest of Assyria and to work on improving relations. Tudḫaliya's letter did little to dissuade him, who saw through the empty flatteries and attacked and conquered the lands in question in his first few years as king. According to his inscriptions, the conquest was widely celebrated as one of his outstanding early achievements.

Like his predecessors, Tukulti-Ninurta's main focus was on Babylonia. His first act in regard to his southern neighbor, Kashtiliash IV, was to escalate conflict through claiming "traditionally Assyrian" lands along the eastern Tigris. Tukulti-Ninurta shortly thereafter invaded Babylonia through what modern historians generally regard to be an unprovoked attack. In the contemporary Tukulti-Ninurta Epic, a propaganda epic used to justify his exploits, the king is described as acting according to divine order against Kashtiliash, who is described as vile ruler, abandoned by the gods. In the text, he is accused of various atrocities, including attacking Assyria, violating temples, and deporting or killing civilians. Though there is no evidence for these accusations, they might well have been based on real events, albeit probably exaggerated. According to the Tukulti-Ninurta epic, he marched south to the Diyala River and began targeting Babylonian cities, including Sippar and Dur-Kurigalzu. Kashtiliash then attacked the Assyrians, confident that he would be victorious, but he was defeated and then avoided conflict himself for the rest of the war. Tukulti-Ninurta eventually emerged as the winner, conquering Babylonia c. 1225 BC, dragging Kashtiliash back to Assyria as a prisoner, and assuming the ancient title "king of Sumer and Akkad". Given that some inscriptions report "Assyrian refugees" from Babylonia and that some soldiers were "starving", it appears that the victory was a costly one. Tukulti-Ninurta's rule over Babylonia, which nominally placed territories as far south as the Persian Gulf under Assyrian rule, lasted for several years and began the apex of Middle Assyrian power, though Assyrian domination appears to have been rather indirect.

Tukulti-Ninurta experienced some difficulties in keeping his empire together, particularly in Babylonia. Though the period after Kashtiliash's deposition is poorly attested in Babylonia, it appears that there was a second Assyrian campaign directed towards the south c. 1222 BC, after the rule of Tukulti-Ninurta's vassal kings Enlil-nadin-shumi and Kadashman-Harbe II, which resulted in the accession of another vassal, Adad-shuma-iddina. Because Tukulti-Ninurta was able to come to Babylon as a guest in c. 1221 BC and make offerings to the Babylonian gods, it is clear that Adad-shuma-iddina enjoyed Assyrian support for his rule. Though this campaign was followed by several years of peace, it is clear that Adad-shuma-iddina eventually stopped acting like a puppet ruler. Though Tukulti-Ninurta forgave him for a revolt in which he seized the city of Lubdi, a second revolt by Adad-shuma-iddina in c. 1217 BC was met with a third campaign against Babylon, in which Tukulti-Ninurta looted the city and carried off the religiously important Statue of Marduk (Marduk being Babylonia's national deity) to Assyria. He assumed the further style "king of the extensive mountains and plains" and claimed to rule from the "Upper Sea to the Lower Sea" and that he received tribute "from the four quarters". In one of his inscriptions, Tukulti-Ninurta went as far as proclaiming himself to be the sun-god Shamash incarnated, titling himself šamšu kiššat niše ("sun[god] of all people"). This claim was highly unusual for an Assyrian king to make as the Assyrian rulers were generally not regarded to be divine figures themselves.

The last Babylonian campaign did not resolve all of Tukulti-Ninurta's problems; the Assyrian army at times had to be deployed to the mountains to the northwest and northeast of the Assyrian heartland to quell uprisings and soon enough, a Babylonian uprising led by Adad-shuma-usur, perhaps a son of Kashtiliash IV, drove the Assyrians out of Babylonia c. 1216 BC. Tukulti-Ninurta is recorded to have complained to the Hittite king Šuppiluliuma II, at this point an ally of Assyria and expected to cooperate militarily, that he had "remained silent" on the "illegal seizure of power" of Adad-shuma-usur.

In addition to his campaigns and conquests, Tukulti-Ninurta is also famous for the most dramatic construction project of the entire Middle Assyrian period: the construction of a new capital city, Kar-Tukulti-Ninurta, named after himself (the name meaning "fortress of Tukulti-Ninurta"). Founded in the eleventh year of his reign (c. 1233 BC), the construction and brief occupation of the city was the only time the Assyrian capital was moved before the Neo-Assyrian period, centuries later. After Tukulti-Ninurta's death, the capital was transferred back to Assur.

First period of decline

Inscriptions from the late reign of Tukulti-Ninurta showcase increasing internal isolation, as many among the powerful nobility of Assyria grew dissatisfied with his rule, especially after the loss of Babylonia. In some of his own inscriptions, Tukulti-Ninurta appears to lament the losses since his glory days. His long and prosperous reign ended with his assassination, which was followed by inter-dynastic conflict and a significant drop in Assyrian power. Though some historians have attributed the assassination to Tukulti-Ninurta's moving the capital away from Assur, a possibly sacrilegious act, it is more probable that it was the result of the growing dissatisfaction during his late reign. Later chroniclers blame the assassination on his son Ashur-nasir-apli, perhaps a misspelled version of the name of his successor Ashur-nadin-apli (r. c. 1206–1203 BC). Another leader of the conspiracy appears to have been the grand vizier and vassal king of Hanigalbat Ili-ipadda, who retained a prominent position at the court for years thereafter. Ashur-nadin-apli was after his short reign succeeded by two of his brothers, Ashur-nirari III (r. c. 1202–1197 BC) and Enlil-kudurri-usur (r. c. 1196–1192 BC), who also ruled only briefly and were unable to maintain Assyrian power. Though the line of Assyrian kings continued uninterrupted over the course of the decline, Assyria became restricted mostly to just the Assyrian heartland. The decline of the Middle Assyrian Empire broadly coincided with the Late Bronze Age collapse, a time when the Ancient Near East experienced monumental geopolitical changes; within a single generation, the Hittite Empire and the Kassite dynasty of Babylon had fallen, and Egypt had been severely weakened through losing its lands in the Levant. Modern researchers tend to varyingly ascribe the collapse to large-scale migrations, invasions by the mysterious Sea Peoples, new warfare technology and its effects, starvation, epidemics, climate change and unsustainable exploitation of the working population.

Enlil-kudurri-usur enjoyed a much poorer relationship with the line of vassal rulers of Hanigalbat, perhaps because he might not have supported the assassination of his father. Such a poor relationship was dangerous given that these vassal rulers were also members of the Assyrian royal family, as descendants of Adad-nirari I. At some point during Enlil-kudurri-usur's reign, Ili-ipadda's son Ninurta-apal-Ekur traveled to Babylonia where he met with Adad-shuma-usur. With Babylonian support, Ninurta-apal-Ekur then invaded Assyria and defeated Enlil-kudurri-usur in battle. According to the Babylonian Chronicles, he was captured and surrendered to the Babylonians by his own people. Ninurta-apal-Ekur then became king, ending the line of rulers who were direct descendants of Tukulti-Ninurta. During his reign, c. 1191–1179 BC, Ninurta-apal-Ekur proved to be, like his immediate predecessors, unable to do much about the collapse of the empire. In the reign of his son, Ashur-dan I (r. c. 1178–1133 BC), the situation improved somewhat as can be gathered from a campaign directed by Ashur-dan I against the Babylonian king Zababa-shuma-iddin, illustrating that hopes for gaining control of at least some southern lands and reasserting superiority over Babylonia had not been completely abandoned.

After Ashur-dan's death in 1133 BC, his two sons Ninurta-tukulti-Ashur and Mutakkil-Nusku struggled for power, with Mutakkil-Nusku emerging victorious but then only ruling for less than a year. Mutakkil-Nusku began a conflict with the Babylonian king Itti-Marduk-balatu over control of the city of Zanqi or Zaqqa, which continued in the reign of his son and successor Ashur-resh-ishi I (r. 1132–1115 BC). In the Synchronistic History (a later Assyrian document), further tensions at Zanqi are described between Ashur-resh-ishi and the Babylonian king Nebuchadnezzar I, which included a battle in which the Babylonians burned down their own siege engines so that they would not be captured by the Assyrians. Though the Synchronistic History describes Assyria as in danger of Babylonian aggression in the reign of Nebuchadnezzar's father and predecessor Ninurta-nadin-shumi, it casts Ashur-resh-ishi as a savior of the empire, who defeated Nebuchadnezzar in several battles and was able to defend the southern Assyrian border. Ashur-resh-ishi as such began to reverse the decades of Assyrian decline and in his inscriptions claimed the epithet "avenger of Assyria" (mutēr gimilli māt Aššur).

Second period of expansion and consolidation

Ashur-resh-ishi's son and successor Tiglath-Pileser I (r. 1114–1076 BC) inaugurated a second period of Middle Assyrian ascendancy. Owing to his father's victories against Babylon, Tiglath-Pileser was free to divert his attention to other regions and not worry about a southern attack. Texts written already during his first few regnal years demonstrate that Tiglath-Pileser ruled with more confidence than his predecessors, using titles such as "unrivalled king of the universe, king of the four quarters, king of all princes, lord of lords" and epithets such as "splendid flame which covers the hostile land like a rain storm". In his first year as king, Tiglath-Pileser defeated the Mushki, a tribe who had taken control of various lands in the north fifty years prior. The inscriptions mention that no king had defeated them in battle before and that their 20,000 men strong army, led by five kings, was defeated by Tiglath-Pileser, who however allowed the 6,000 surviving enemies to settle in Assyria as his subjects. One of the Mushki strongholds, the city of Katmuḫu in the northeast, continued to be troublesome for a few years before it was reconquered, looted and its king, Errupi, was deported. Numerous other sites in the northeast were also conquered and incorporated into his empire.

Tiglath-Pileser also went on significant campaigns in the west. The cities of northern Syria, which had ceased to pay tribute decades prior, were reconquered and the Kaskians and Urumeans, tribes who had also settled in the region, voluntarily submitted to him immediately upon the arrival of his army. He also waged war on the Nairi people in the Armenian highlands. Famed for their knowledge of horse breeding, his self-admitted goal of this campaign was to acquire more horses for the Assyrian army. It is clear from his inscriptions that the goal of the campaigns were to instill respect among the rulers of the lands formerly subordinate to Assyria, to reconquer the old Assyrian borders, and to go beyond them; "Altogether, I conquered 42 lands and their rulers from the other side of the Lower Zab in distant mountainous regions to the other side of the Euphrates River, people of Ḫatti, and the Upper Sea in the west – from my accession year to my fifth regnal year. I subdued them to one authority, took hostages from them, (and) imposed upon them tribute and impost".

Tiglath-Pileser's inscriptions are the first Assyrian inscriptions to describe punitive measures against rebelling cities and regions in any detail. A more important innovation was increasing the size of the Assyrian cavalry and introducing war chariots on a grander scale than previous kings. Chariots were also increasingly used by Assyria's enemies. In the final years of his reign, he twice engaged the Babylonian king Marduk-nadin-ahhe in battles with a great number of chariots. Though he did not conquer Babylonia, several cities, including Babylon itself, were successfully attacked and looted. He was probably unable to conquer Babylonia since a significant amount of attention needed to be diverted to the Aramean tribes in the west. Though he was one of the most powerful kings of the Middle Assyrian period, succeeding in imposing tribute from as far away as Phoenicia, his achievements were not long-lasting and several territories, especially in the west, were likely lost again before his death.

As a result of Tiglath-Pileser's campaigns, Assyria became somewhat overstretched and his successors had to adapt to be on the defensive. His son and successor Asharid-apal-Ekur (r. 1075–1074 BC) ruled too briefly to do anything and his successor Ashur-bel-kala (r. 1073–1056 BC), another son of Tiglath-Pileser, managed to only briefly follow in his father's footsteps. Ashur-bel-kala campaigned in the mountains to the northeast and the Levant and is recorded to have received gifts from Egypt. Though political objectives had thus not changed since Tiglath-Pileser's time, Ashur-bel-kala too had to divert significant attention to the Arameans. Due to the Aramean tactics of avoiding open battle and instead attacking the Assyrians in numerous minor skirmishes, the Assyrian army could not take advantage of their technical and numerial superiority. The Arameans were not Ashur-bel-kala's only enemies in the west, given that he is also recorded to have fought against Tukulti-Mer, king of Mari. The conflict with Marduk-nadin-ahhe in Babylonia continued under Ashur-bel-kala, though it was eventually resolved diplomatically. After the death of Marduk-nadin-ahhe's successor Marduk-shapik-zeri in c. 1065 BC, Ashur-bel-kala was even able to intervene and install the unrelated Adad-apla-iddina as king of Babylon. Adad-apla-iddina's daughter then married Ashur-bel-kala, bringing peace to the two kingdoms. Though he shared his father's ambition, and claimed the title "lord of all" after his victorious campaigns in Syria, Babylonia and the northeastern mountains, Ashur-bel-kala was ultimately unable to surpass Tiglath-Pileser and his successes were built on shaky foundations.

Second period of decline

Century of crisis

Ashur-bel-kala's son and successor Eriba-Adad II (r. 1056–1054 BC), and generations of kings thereafter, were unable to maintain the achievements of their predecessors. The period of decline initiated after Ashur-bel-kala's death was not reversed until the middle of the 10th century BC. Though this period is poorly documented, it is clear that Assyria underwent a major crisis.

Although Assyria was only marginally affected by the Late Bronze Age collapse, the collapse caused great changes in the geopolitics of the lands surrounding Assyria. In large part, the power vacuum left by the Hittites and Egyptians in Anatolia and the Levant allowed various ethno-tribal communities and states to take their place. In northern Anatolia and northern Syria, the Luwians seized power, forming the Syro-Hittite states. In Syria, the Arameans grew increasingly prominent. In Palestine, the Philistines and Israelites carved out realms of their own, eventually coalescing into the Kingdom of Israel. Though cuneiform had previously been the main writing system of these regions, the rise of new peoples and realms led to cuneiform being replaced in the west by more simple alphabetic writing systems. Out of the new players on the scene, the Arameans, through their at times eastward movements, had the most effect on Assyria. Documents as old as from the reign of Tiglath-Pileser I demonstrate that even at that early stage, Aramean raids penetrated deep into the Assyrian heartland, at one point reaching Assur itself. The Arameans were tribal and their attacks were uncoordinated raids carried out by individual groups. As such, Assyrian kings were able to defeat several Aramean groups in battle. The guerilla tactics and ability of the Arameans to quickly withdraw into difficult terrain however prevented Assyrian armies from ever achieving a lasting decisive victory. From the death of Ashurnasirpal I (r. 1049–1031 BC) to the end of the Middle Assyrian period more than a century later, no surviving Assyrian royal inscriptions describe any military activities whatsoever. Though kings from this time, such as Shalmaneser II (r. 1030–1019 BC) and Ashur-rabi II (r. 1012–972 BC), used names that proudly echoed those of earlier successful rulers, suggesting a desire to restore old glory, later Assyrian documents saw this time as one of painful losses of territory. By 1000 BC, Assyria was at the low point of its power, with many previously large settlements lying in ruins and local rulers battling new tribal chiefs for control of lands that were previously part of the empire. The Assyrian heartland continued to remain intact, however, protected due to its geographical remoteness.

Beginning of the Assyrian reconquista

The Assyrian kings never ceased to believe that the lost lands would eventually be retaken. In the end, the collapse of the Hittites and the Egyptian lands in the Levant benefitted Assyria; with the old empires shattered, the fragmented territories surrounding the Assyrian heartland would eventually prove to be easy conquests for the Assyrian army. The reign of Ashur-dan II (r. 934–912 BC) effectively terminated the poorly documented second period of Middle Assyrian decline. Multiple inscriptions survive from Ashur-dan's time, several of which describe campaigns in the peripheries of the Assyrian heartland, illustrating that Assyrian power was beginning to resurge. Ashur-dan's campaigns were mainly focused on the northeast and northwest. Among the victories recorded in his inscriptions was the conquest of Katmuḫu, which once again had gained independence during the decline. According to the inscription, Ashur-dan captured Katmuḫu, razed the city's royal palace, brought its king to Arbela, flayed and executed him, and then displayed his skin on the wall of one of his cities. Assyrian reconquest meant that a high level of threat had to be established in order to keep the vassals in line; an explanation for the brutality and violence of certain acts (such as Ashur-dan's treatment of the defeated king) committed by the Assyrian kings. The descriptions of such acts in inscriptions do not necessarily reflect the truth given that they also served as intimidating tools for propaganda and psychological warfare.

The campaigns of Ashur-dan paved the way of grander efforts to restore and expand Assyrian power, beginning in the reign of his son and successor Adad-nirari II (r. 911–891 BC), whose accession conventionally marks the beginning of the succeeding Neo-Assyrian Empire. Although historically sometimes treated as a separate and distinct entity from the Middle Assyrian Empire, the Neo-Assyrian Empire was clearly the direct continuation of the Middle Assyrian civilization given that the line of kings and inhabitation of the Assyrian heartland was continuous. The inscriptions of early Neo-Assyrian kings typically treat their wars of expansions as reconquests of territory lost during the decline of the Middle Assyrian Empire.