Đại Việt–Khmer War

The conflicts

In 1127, Suryavarman II demanded Vietnamese emperor Lý Dương Hoán to pay tribute for the Khmer Empire, but the Vietnamese refused. Suryavarman decided to expand his territory northward into Vietnamese territory. The first attack was in 1128 when King Suryavarman led 20,000 soldiers from Savannakhet to Nghệ An, where they were routed in battle. The following year Suryavarman continued skirmishes on land and sent 700 ships to bombard the coastal areas of Đại Việt. In 1132, he persuaded Cham king Jaya Indravarman III to join forces with him to attack Đại Việt, where they briefly seized Nghệ An and pillaged the coastal districts of Thanh Hoá.

In 1136, a Vietnamese force under Đỗ Anh Vũ counterattacked the Khmer Empire across modern-day Laos with 30,000 men, but later retreated. The Cham thereupon made peace with the Vietnamese, and when Suryavarman renewed the attack, Jaya Indravarman refused to cooperate with the Khmers. After a failed attempt to seize seaports in southern Đại Việt, Suryavarman turned to invade Champa in 1145 and sacked Vijaya, ending the reign of Jaya Indravarman III and destroying the temples at Mỹ Sơn. In 1147 when a Panduranga prince named Sivänandana was enthroned as Jaya Harivarman I of Champa, Suryavarman sent an army consisting of Khmers and defected Chams under the command of the senäpati (military commander) Sankara to attack Harivarman, but was defeated in the battle of Räjapura in 1148. Another stronger Khmer army also suffered the same wretchedness fate at the battles of Virapura (present-day Nha Trang) and Caklyaṅ. Michael Vickery (2011) conjectures that both Räjapura, Virapura, and Caklyaṅ's modern-day precise locations are unknown, but proposes that those medieval locations should be somewhere between Qui Nhon and Phan Rang.

Aftermath

After a failed attempt to seize seaports in southern Đại Việt, Suryavarman turned to invade Champa in 1145 and sacked Vijaya, ending the reign of Jaya Indravarman III and destroying the temples at Mỹ Sơn. Inscriptional evidence suggests that Suryavarman II died between 1145 AD and 1150 AD, possibly during a military campaign against Champa. He was succeeded by Dharanindravarman II, a cousin, son of the brother of the king's mother. A period of weak rule and feuding began.

The three provinces Dia Ly (Jriy), Bo Chinh (Traik), Malinh, which Champa had lost to the Đại Việt around 1069–1076, were probably returned to the Cham sphere of influence during 1131-1136, which was testified by both Chinese and Cham sources.