后杭爱省
After Modu, later leaders formed a dualistic system of political organisation with the left and right branches of the Xiongnu divided on a regional basis. The "chanyu" or "shanyu", a ruler equivalent to the Emperor of China, exercised direct authority over the central territory. Longcheng (蘢城) became the annual meeting place and served as the Xiongnu capital. The ruins of Longcheng were found south of Ulziit District, Arkhangai Province in 2017.