The term “ancient China” usually refers to the roughly two millennia before the Common Era, during which time, according to traditional Chinese historiography, the earliest civilization of China was created under the Three Dynasties (
Sandai
) – Xia, Shang, and Zhou (K. C. Chang 1983a). Traditional chronology places Xia between 2205 and 1766
BCE
, Shang between 1766 and 1122
BCE
, and Zhou between 1122 and 256
BCE
. Only the last date – the year the rising power of Qin vanquished the state of Zhou, on its way to creating the first unified empire in 221
BCE
– is certain. The others have been repeatedly and convincingly rejected, and continue to be debated, because they are irresoluble (K. C. Chang 1983a; Shaughnessy 1999; Keightley 1999b). Some scholars even regard the Xia dynasty as sheer invention. For the purposes of discussing ancient Chinese migration, we will include territorial expansions and consolidation of the Former (Western) Han dynasty (202
BCE–
8
CE
) because they bring to a conclusion the trends that started earlier in the ancient period.