Lý Thánh Tông
In 1069, Champa Kingdom gained support from the Song dynasty and stopped paying tributary to Đại Việt. As the result, the emperor Lý Thánh Tông ordered an expedition against Champa and successfully captured King Rudravarman III of Champa. Rudravarman III had to sign a treaty with Lý Thánh Tông to cede Quảng Trị and Quảng Bình to Đại Việt which massively contributed to the expansion of Đại Việt territory. Champa also had to restore the tributary system to Lý dynasty.