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).
History of Mongolia
The first significant appearance of nomads came late in the 3rd century BC, when the Chinese repelled an invasion of the Xiongnu (Hsiung-nu in Wade–Giles romanisation) across the Yellow River from the Gobi. A Chinese army, which had adopted Xiongnu military technology—wearing trousers and using mounted archers with stirrups—pursued the Xiongnu across the Gobi in a ruthless punitive expedition. Fortification walls built by various Chinese warring states were connected to make a 2,300-kilometre Great Wall along the northern border, as a barrier to further nomadic inroads.