[13][14][15] In approximately 257 BCE, Văn Lang was purportedly annexed by the Âu Việt leader Thục Phán, who according to traditional Vietnamese historiography, was either the prince or king of Shu.

King An Duong is the first figure in Vietnamese history documented by reliable historic sources, yet most of what we know about his reign survived in legendary form.

[20]Cổ Loa, the largest prehistoric moated urban settlement in Southeast Asia,[21] was the first political hub of Vietnamese civilization in the pre-Sinitic era,[22] encompassing 600 hectares (1,500 acres),[23][24] and requiring as many as 2 million cubic meters of material.

According to this legend, when being built, the citadel saw all the work mysteriously undone by a group of spirits led by a thousand-year-old white chicken seeking to avenge the son of the previous King.

It was then called "Saintly Crossbow of the Supernaturally Luminous Golden Claw" (靈光金爪神弩; SV: Linh Quang Kim Trảo Thần Nỏ); one shot could kill 300 men.

[‡ 7][36][38][37] It is possible that the magical crossbow may have been a type of new model army under Cao Thông's command that was influenced by the technologies and innovations from the Warring States.

"Seals and ribbons" were bestowed upon these local leaders as their status symbol, in return, they paid "tribute to a suzerain" but the Han officials considered this as "taxes".

[54][55] Before that, while "some form of nominal northern hegemony was installed",[56] there was no evidence that any Chinese-style enterprise controlled the region during the second or first centuries BCE as certain historical accounts are relatively Sinocentric and misleading as to the nature of Proto-Vietnamese society before the "real, later imposition of full Chinese power.

"[57] Based on evidence from the historical and archaeological records, Kim (2015) believed that a "highly centralized, overarching state-level society with enduring political institutions and structure" between 300 and 100 BCE was responsible for the construction of the Cổ Loa settlement.

They denied in situ cultural evolution or social complexity, attributing any development to sinicization,[64] though they were aware of this "stable, structured, productive, populous, and relatively sophisticated" society that they encountered.

[67] In addition, they also practiced levirate, meaning widows had a right to marry a male relative of her late husband, often his brother, to obtain heirs.

This practice provided an heir for the mother, protecting widows' interests and reflecting female authority, although some patriarchal societies used it to keep wealth within the male family bloodline.

[77] French linguist Michel Ferlus in 2009 concludes that the Vietnamese are the "most direct heirs" of Đông Sơn culture (c. 7th BC to 1st AD), which was "precisely located in the North of Vietnam".

[77] Archaeological evidence reveals that during the pre-Dongson period, the Red River Delta was prominently Austroasiatic, such as genetic samples from the Mán Bạc burial site (dated 1,800 BCE) have close proximity to modern Austroasiatic speakers,[79] and then during the Dongson period, genetic examples yield to a significant proportion of Tai stocks (known as Au, Li-Lao) possibly living along with Vietic speakers.

[80] The economy was characterized by agriculture with wet rice cultivation, draft animals, metal plowshares, axes and other tools, as well as irrigation complexes.

[65] The cultivation of irrigated rice may have started in the beginning of the second millennium BCE, evidenced by findings from palynological sequences,[81][65] while metal tools were regularly used before any significant Sino-Vietic interaction.

[82] Northern Vietnam was also a major hub of interregional access and exchange, connected to other area through an extensive extraregional trade network, since well before the first millennium BC, thanks to its strategic location, access to key interaction routes and resources, including proximity to major rivers or the coast[note 4] and a high distribution of copper, tin, and lead ores.