King An Duong Vuong of Thuc, the upland neighbor to the kingdom of Van Lang, overthrows the last Hung king in the third century BCE.

An Duong Vuong unites Van Lang with Thuc to form Au Lac, building his capital and citadel at Co Loa, thirty-five kilometers north of present-day Hanoi.

An Duong's kingdom is short-lived, however, being conquered in 208 BCE by the army of the Chinese Qin dynasty (221-207 BCE) military commander Trieu Da (Zhao Tuo in Chinese).

Reluctant to accept the rule of the Qin dynasty's successor, the new Han dynasty (206 BCE-CE 220), Trieu Da combines the territories under his control in southern China and northern Vietnam and establishes the kingdom of Nam Viet (Nan Yue in Chinese), meaning Southern Viet.

Viet (Yue) is the term applied by the Chinese to the various peoples on the southern fringes of the Han empire, including the people of the Red River Delta.

Trieu Da divides his kingdom of Nam Viet into nine military districts; the southern three (Giao Chi, Cuu Chan, and Nhat Nam) include the northern part of present-day Vietnam.

The Lac lords continue to rule in the Red River Delta, but as vassals of Nam Viet.