 Complete the following phrase:  Since 905, Tĩnh Hải circuit had been ruled by local Vietnamese governors like an autonomous state. Tĩnh Hải circuit had to paid tributes for Later Liang dynasty to exchange political protection. In 923, the nearby Southern Han invaded Jinghai but was repelled by Vietnamese leader Dương Đình Nghệ. In 938, the Chinese state Southern Han once again sent a fleet to subdue the Vietnamese. General Ngô Quyền r. 939944, Dương Đình Nghệs son-in-law, defeated the Southern Han fleet at the 