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 from the Mạc royal relatives fled on the northern mountains inside the province of Cao Bằng and ongoing to rule there till 1677 https://vf55509865.blogscribble.com/31127028/a-secret-weapon-for-6623