Following military successes against the Liang and the Chen, the Northern Zhou general Yang Jian (541-604) pronounced himself emperor, taking the name Wendi, and founded the Sui dynasty in 581. This brief but significant dynastic rule established political and social stability. He undertook an extensive program of works including extending the Great Wall and the beginnings of the Grand Canal. The second emperor, Yangdi (569-617), restored diplomatic relations with Japan and extended trade to Central Asia.