The civil war concerning the Lê-Trịnh and Mạc dynasties resulted in 1592, when the military of Trịnh Tùng conquered Hanoi and executed king Mạc Mậu Hợp. Survivors of the Mạc royal spouse and children fled for the northern mountains from the province of Cao Bằng and ongoing to rule there https://vi-t-nam98753.bloggazza.com/30298710/việt-nam-an-overview