Trịnh lords
Both the Trịnh and Nguyễn families were descended from aides to the hero-Emperor Lê Lợi who liberated Đại Việt from Chinese rule of Ming Dynasty and started the Lê Dynasty in 1428. By 1520 a succession of weak emperors had brought the country into a state of civil war (see Lê Dynasty's civil war). For the next 20 years the Trịnh and Nguyễn clans fought as allies against the usurper Mạc Đăng Dung to restore Đại Việt under rule of Lê Emperor. When Lê dynasty was restored in 1533, the Mạc dynasty had to retreated to Cao Bang. Nguyễn Kim, the father of the first Nguyễn lords, married his daughter to his subordinate Trịnh Kiểm, the first of Trịnh lords. Thus the Trịnh lords and Nguyễn lords are blood related.