The earliest reference of the name Vientiane can be seen on a Vietnamese inscription of Duke Đỗ Anh Vũ, dated 1159 during the Khmer-Viet conflict. The inscription says that in 1135, Văn Đan (Vientiane), a vassal of Zhenla (Khmer Empire), invaded Nghe An, but was repelled by the Duke; the Duke led an army chased the invaders as far as Vũ Ôn? (unattested), and then returned with captives.