Cổ Loa Citadel is an important fortified settlement and archaeological site in present-day Hanoi's Đông Anh district, roughly 17 kilometers north of present-day Hanoi, in the upper plain north of the Red River. Various relics of the Bronze Age Phùng Nguyên culture and Đông Sơn culture have been found in Cổ Loa, although it was later established as the capital of Âu Lạc Kingdom during the 3rd century BCE. It might be the first political center of the Vietnamese civilization. The settlement’s concentric walls resemble a snail’s shell; it had an outer embankment covering 600 hectares.

The Baiyue, Hundred Yue, or simply Yue, were various ethnic groups who inhabited the regions of Southern China and Northern Vietnam during the 1st millennium BC and 1st millennium AD. They were known for their short hair, body tattoos, fine swords, and naval prowess.