The civil war among the Lê-Trịnh and Mạc dynasties led to 1592, when the military of Trịnh Tùng conquered Hanoi and executed king Mạc Mậu Hợp. Survivors of the Mạc royal family members fled to the northern mountains inside the province of Cao Bằng and continued to rule there right up until 1677 when Trịnh Tạc conquered this pr