Oromia

It is bordered by the Somali Region to the east; the Amhara Region, the Afar Region and the Benishangul-Gumuz Region to the north; Dire Dawa to the northeast; the South Sudanese state of Upper Nile, Gambela Region, South West Ethiopia Region, Southern Nations, Nationalities, and Peoples' Region and Sidama Region to the west; the Eastern Province of Kenya to the south; as well as Addis Ababa as an enclave surrounded by a Special Zone in its centre and the Harari Region as an enclave surrounded by East Hararghe in its east.

In August 2013, the Ethiopian Central Statistics Agency projected the 2017 population of Oromia as 35,467,001, making it the largest regional state by population. It is also the largest regional state, covering 353,690 square kilometres (136,560 sq mi).

History

Evidence from Muslim geographers and Ethiopian royal chronicles demonstrates that Oromos were in the Ethiopian Highlands as early as the Middle Ages.

These societies maintained dynamic relations across frontiers—from the Christianized provinces of northern Shewa to the Muslim centers of Harar.

Modern day Shewa was historically divided into three subdivisions: Gerra-Medir, Mamma-Midir, and Lallo-Midir. These names derive from three early rulers—Gerra, Mamma, and Lallo—who governed the region before the rise of the Shewan dynasty. Accounts describe them as Christianized rulers.

Arabic sources from the 13th century describe a region called Gazla, also rendered as Karla or Garla. The Andalusian geographer Ibn Saʿīd al-Maghribī provided one of the earliest known accounts:

"The land of Kazla begins from the equator, neighbouring the Zanj of al-Habasha, and stretches south of Mount Murus, which is said to provide the people of Janbeyta and those regions with gold and silver mines. It lies four days' journey from Janbeyta. To its east and north it extends from there, running eastward and bending northward until it cuts across the Nile of al-Habasha and ends at their sea."

Historians such as Tadeusz Lewicki identified Gazla with the interior highlands of southern Ethiopia, likely inhabited by Cushitic-speaking peoples—possibly early Oromo populations. Its location near the sources of the Nile and south of the Abyssinian kingdom situates it between modern-day Bale, Arsi, and Hararghe. The references to mineral wealth and proximity to trade centers imply that Gazla was a politically organized and economically connected region.

The description of Gazla "cutting across the Nile of al-Habasha and ending at their sea" indicates a geographical span from the Ethiopian interior to the Indian Ocean coast. This aligns with evidence for early trade routes linking the Ethiopian plateau with ports such as Mogadishu, Marka, and Brava, suggesting that Gazla served as a key corridor of cultural and commercial exchange between the interior and the Zanj coast.

In medieval Ethiopian Christian literature, the term Arämi (አራሚ) was used to denote pagans, non-Christians, or infidels. It was especially applied to non-Christian Oromo groups and to Muslims living along the southern frontier of the Christian kingdom. The term could also function interchangeably with Tanbalat for Muslims, and in some cases was even extended to other foreigners.

A miracle of Saint Täklä Haymanot, edited by Getatchew Haile (1984), refers to "the seven regions of the Arämi (Muslims)", which parallels the seven Islamic provinces mentioned by Arabic writers concerning the early Kingdom of Ifat.

This linguistic and historical correspondence suggests that the Arämi of Ethiopian chronicles and the Gazla of Arabic geography refer to overlapping frontier zones — multi-religious regions where Oromo, Harla, Somali, and other Cushitic peoples interacted with both Christian and Muslim influences.

The Oromo remained independent until the last quarter of the 19th century, when they lost their sovereignty. From 1881 to 1886, Emperor Menelik II conducted several unsuccessful invasion campaigns against their territory. The Arsi Oromo demonstrated fierce resistance against this Abyssinian conquest, putting up stiff opposition against an enemy equipped with modern European firearms. They were ultimately defeated in 1886.

In the 1940s some Arsi Oromo together with people from Bale province joined the Harari Kulub movement, an affiliate of the Somali Youth League that opposed Amhara Christian domination of Hararghe. The Ethiopian government violently suppressed these ethno-religious movements. During the 1970s the Arsi formed alliances with Somalia.

In 1967, the imperial regime of Haile Selassie I outlawed the Mecha and Tulama Self-Help Association (MTSHA), an Oromo social movement, and conducted mass arrests and executions of its members. The group's leader, Colonel General Tadesse Birru, who was a prominent military officer, was among those arrested. The actions by the regime sparked outrage among the Oromo community, ultimately leading to the formation of the Oromo Liberation Front in 1973. The Oromos perceived the rule of Emperor Haile Selassie as oppressive, as the Oromo language was banned from education and use in administration, and speakers were privately and publicly mocked. The Amhara culture dominated throughout the eras of military and monarchic rule.

Both the imperial and the Derg government relocated numerous Amharas into southern Ethiopia, including the present day Oromia region, in order to alleviate drought in the north of the country. They also served in government administration, courts, church and even in school, where Oromo texts were eliminated and replaced by Amharic. Further disruption under the Derg regime came through the forced concentration and resettlement of peasant communities in fewer villages. The Abyssinian elites perceived the Oromo identity and languages as opposing the expansion of an Ethiopian national identity.

In the early 1990s, the Ethiopian Democratic People's Republic began to lose its control over Ethiopia. The OLF failed to maintain strong alliances with the other two rebel groups at the time: the Eritrean People's Liberation Front (EPLF) and the Tigray People's Liberation Front (TPLF). In 1990, the TPLF created an umbrella organization for several rebel groups in Ethiopia, the Ethiopian People's Revolutionary Democratic Front (EPRDF). The EPRDF's Oromo subordinate, the Oromo People's Democratic Organization (OPDO) was seen as an attempted replacement for the OLF.

On 28 May 1991, the EPRDF seized power and established a transitional government. The EPRDF and the OLF pledged to work together in the new government; however, they were largely unable to cooperate, as the OLF saw the OPDO as an EPRDF ploy to limit their influence. In 1992, the OLF announced that it was withdrawing from the transitional government because of "harassment and [the]assassinations of its members". In response, the EPRDF sent soldiers to destroy OLA camps. Despite initial victories against the EPRDF, the OLF were eventually overwhelmed by the EPRDF's superior numbers and weaponry, forcing OLA soldiers to use guerrilla warfare instead of traditional tactics. In the late 1990s, most of the OLF's leaders had escaped Ethiopia, and the land originally administered by the OLF had been seized by the Ethiopian government, now led by the EPRDF.

Prior to the establishment of present-day Addis Ababa the location was called Finfinne in Oromo, a name which refers to the presence of hot springs. The area was previously inhabited by various Oromo clans.

In 2000, Oromia's capital was moved from Addis Ababa to Adama. Because this move sparked considerable controversy and protests among Oromo students, the Oromo Peoples' Democratic Organization (OPDO), part of the ruling EPRDF coalition, on 10 June 2005, officially announced plans to move the regional capital back to Addis Ababa.

Further protests sparked on 25 April 2014, against the Addis Ababa Master Plan, then resumed on 12 September 2015 and continued into 2016, when renewed protests broke out across Ethiopia, centering around the Oromia region. Dozens of protesters were killed in the first days of the protests and internet service was cut in many parts of the region. In 2019, the Irreecha festival was celebrated in Addis Ababa after 150 years of being banned.