Dai Viet (or Annam) has grown weak under a series of ineffectual rulers during intermittent hostilities with China.

Khmer monarch Suryavarman II, seeing opportunity for expansion at the Viets’ expense, coerces the Chams into aiding him against the Vietnamese.

In 1128, he leads a combined Khmer-Cham force of about twenty thousand north along the “old ambassador route” from Savannakhet (in the region of present south-central Laos) to Nghe An (in the region of present northern Vietnam), but the Vietnamese rout the invasion.

In the fall, Suryavarman dispatches over seven hundred ships to ravage Dai Viet’s coastal regions while continuing to skirmish with ground troops.