His antecedents are "cloudy" since the only information provided by written accounts is that his family name was Thục, and his personal name was Phán, which appears to associate him with the ancient state of Shu in what is now Sichuan, conquered by Qin dynasty in 316 BCE. This was also the traditional view of Chinese and Vietnamese historians. Many chronicles including "Records of the Outer Territories of the Jiao province", "Đại Việt sử lược", "Đại Việt sử ký toàn thư" stated that he was a son of King Thục, but they were unable to describe precisely his origin. Later historians had a more nuanced view. In Khâm định Việt sử Thông giám cương mục, the writers expressed doubts about King An Dương Vương's origin, claiming it was impossible for a Shu prince to cross thousands of miles, through forests and many states to invade Văn Lang. In 1963, an oral tradition of Tày people in Cao Bằng titled "Cẩu chủa cheng vùa" was recorded. According to this account, at the end of Hồng Bàng dynasty, there was a kingdom called Nam Cương (lit. “southern border), comprising portions of modern-day Cao Bằng and Guangxi. It consisted of 10 regions, in which the King resided in the central one (present-day Cao Bằng Province).The other nine regions were under the control of nine lords. While King An Dương Vương's father (Thục Chế ) died, he was still a child; yet, his intelligence enabled him to retain the throne and all the lords surrendered. Nam Cương became more and more powerful while Văn Lang became weak. Subsequently, he invaded Văn Lang and founded the state of Âu Lạc. The tale is supported by many vestiges, relics and place names in Cao Bằng Province. The assumption about his origin as a local inhabitant has also been reflected in various fairy tales, registers, worships and folk memories. According to historian Đào Duy Anh in "Đất nước Việt Nam qua các đời: nghiên cứu địa lý học lịch sử Việt Nam", the southern part of Zuo River, the drainage basin of You River and the upstream area of Lô River, Gâm River, and Cầu River are inhabited by Âu Việt tribes with the supreme leader Thục Phán.