Chronology
c. 700–209 BC: A pastoral nomad society developed north of China. Nomadic people who lived around the perimeters of the Chinese kingdoms were generally known as the Rong people. There were petty raids on China, particularly against the states of Zhao and Qin, but no organized nomadic state.
244 BC: First mention of Xiongnu. 221 BC: Qin dynasty founded. 215 BC: Qinshihuang builds the Great Wall (which included linking existing walls of the Warring States) and Meng Tian drives the Xiongnu out of the Ordos Loop.
Read more about this topic: Xiongnu