Architecture of Mongolia
The Xiongnu confederation ruled present-day Mongolia from the third century BCE through the first century CE, living in portable, round tents on carts and round yurts. The Xiongnu aristocracy lived in small palaces, and their villages were protected by huge walls. S. I. Rudenko also mentions capital construction built of logs. Archaeological excavations indicate that the Xiongnu had towns; their chief city was Luut Hot (Dragon City).
Han–Xiongnu War
The first half of the 1st century BC witnessed several succession crises for the Xiongnu leadership, allowing the Han empire to reaffirm its control over the Western Regions. Huduershi Chanyu was succeeded by his son Punu (蒲奴) in 46 AD, thus breaking the late Huhanye's orders that only a Xiongnu ruler's brother was a valid successor. Bi (比), the Rizhu King of the Right and Huduershi's nephew, was outraged and was declared a rival Chanyu by eight southern Xiongnu tribes in 48 AD. The Xiongnu confederation fell apart in the Northern Xiongnu and Southern Xiongnu, and Bi submitted to the reign of the Han empire in 50 AD. The Han took control of the Southern Xiongnu under Bi, which had 30–40 thousand troops and a population of roughly twice or thrice the size.