Bắc Thái Nguyên

The northern Thái Nguyên country reaches into the valleys of Cao Bằng, where mountains enclose the fertile basin of Hòa An. After losing Thăng Long, the Mạc rulers retained power in this frontier region. From the late sixteenth century until 1677 they established their court in Cao Bằng and built defences among its valleys, resisting the rival Lê-Trịnh forces that sought to bring the region under their control.

The later city of Cao Bằng lies here.