What is "yamankan"

Nga Yamankan (, ; c. 1039–1084) was governor of Pegu (Bago) from 1077 to 1084, who raised an unsuccessful rebellion against Sawlu of Pagan Dynasty. He nearly succeeded. He captured and killed Sawlu. But he was driven out of Upper Burma by Sawlu's brother, Kyansittha and was killed while in retreat.