Mạc Đăng Dung
In 1527, Mạc Đăng Dung replaced the last Lê emperor Lê Cung Hoàng and established a new dynasty (Mạc dynasty). The Trịnh and Nguyễn lords returned to Thanh Hóa province and refused to accept the rule of the Mạc. All of the region south of the Red River was under their control, but they were unable to conquer Đông Đô for many years. During this time, the Nguyễn–Trịnh alliance was led by Nguyễn Kim; his daughter was married to the Trịnh lord leader, Trịnh Kiểm.