An Dương Vương An Dương Vương is the title of Thục Phán , who ruled over the ancient kingdom of Âu Lạc from 257 to 207 BCE , after defeating the state of Văn Lang and uniting the two tribes Âu Việt and Lạc Việt . He is traditionally said to have lived approximately 100 years . Historical accounts . According to old Vietnamese historical records Đại Việt sử ký toàn thư and Khâm định Việt sử Thông giám cương mục ( " 欽定越史通鑑綱目 " ) , Thục Phán was a prince of the Chinese state of Shu ( 蜀 , which shares the same Chinese character as his surname Thục ) , sent by his father first to explore what are now the southern Chinese provinces of Guangxi and Yunnan and second to move their people to modern - day northern Vietnam during the invasion of the Qin Dynasty . Some modern Vietnamese believe that Thục Phán came upon the Âu Việt territory ( modern - day northernmost Vietnam , western Guangdong , and southern Guangxi province , with its capital in what is today Cao Bằng Province ) . After assembling an army , he defeated King Hùng Vương XVIII , the last ruler of the Hồng Bàng Dynasty , around 257 BCE . He proclaimed himself An Dương Vương ( " King An Dương " ) . He then renamed his newly acquired state from Văn Lang to Âu Lạc and established the new capital at Phong Khê in the present - day Phú Thọ town in northern Vietnam , where he tried to build Cổ Loa Citadel , the spiral fortress approximately ten miles north of that new capital . Thục Phán and Âu Lạc ' s administration . There is not much recorded or written about how the new Âu Lạc was administered and organized . Nonetheless , based on legendary records , he is assumed to have been an astute , intelligent , and significant figure . Certainly he was a talented general who knew how to exploit the confusion and turmoil in China during that period , not only to grab a piece of land for himself but also to secure his state ' s prosperity and survival . Around that same time , various states were fighting for control of China . Eventually , the Qin state rose to power and unified China under Emperor Qin Shi Huang . While Qin Shi Huang ordered the construction of the Great Wall , An Dương Vương had begun the construction of a spiral fortress called Cổ Loa Thành to defend against invasions . The legend of Cổ Loa Thành and the Magic Crossbow . Cổ Loa Thành and Âu Lạc . After Thục Phán defeated the last Hùng Vương king and ascended to the throne as An Dương Vương , he renamed Văn Lang to Âu Lạc and established Cổ Loa Citadel as the new capital . He saw the strategic and geographic importance of Cổ Loa . On two of its sides , Cổ Loa was surrounded by impenetrable mountains and forests . There was also a river flowing by . No one knows why An Dương Vương favored the spiral , shell - like shape of Cổ Loa Citadel , but legend has it that its construction was extremely tough and difficult to complete . Each time it seemed near completion , it was undone at night by a hoard of evil spirits . The legend of Cổ Loa and the Magic Crossbow . An Dương Vương burnt incense , prayed , made offerings , and evoked the gods to help him . One night , in a dream , an old and frail man with long , white hair came to him and told him the only person who could help him build his citadel was a golden turtle that lived somewhere around Cổ Loa . A few days later , while sitting in a boat on the river and thinking about the meaning of his dream , a giant golden turtle suddenly emerged from the water . The golden turtle told An Dương Vương that he would need one of its claws in order to accomplish his plan . Pulling out one of its claws and throwing it to An Dương Vương , the turtle vanished . An Dương Vương had Cao Lỗ , his weaponry engineer , build a crossbow incorporating this claw which could shoot thousands of arrows at once . Indeed right after obtaining this claw , An Dương Vương saw his fortunes change . His capital started taking shape . His kingdom prospered and soon was coveted by neighboring states . Among one of those who coveted his territory was Zhao Tuo ( Triệu Đà in Vietnamese ) , a Qin general who refused to surrender to the newly established Han Dynasty . For a period of ten years around 217 to 207 BCE , Triệu Đà attempted many invasions to conquer Âu Lạc but failed each time due to An Dương Vương ' s military skills and defense tactics . Triệu Đà ' s scheme . Triệu Đà , having been beaten several times , devised a new plan . He negotiated a peace treaty with Âu Lạc . He determined to find out where lay the strength and strategies of his foe . He even went so far as to propose marriage between An Dương Vương ’ s daughter , Princess Mỵ Châu ( ) and his son Trọng Thủy ( , Zhong Shi ) . In time Triệu Đà found out through his daughter - in - law Mỵ Châu that An Dương Vương had a magic crossbow that made him almost invincible . Triệu Đà then he told his son Trọng Thủy to sneak into his father - in - law ' s palace and steal this " magic crossbow " , replacing it with a fake . Triệu Đà , with the magic crossbow in his hands , launched a new attack on his foe and in - law An Dương Vương . The deaths of Mỵ Châu and Trọng Thủy . This time , Cổ Loa fortress fell into Triệu Đà ' s hands . An Dương Vương grabbed Mỵ Châu , his only daughter , and fled the scene of the battle . He rode to the river and encountered the giant golden turtle , which told An Dương Vương , “ The enemy is sitting right behind you ! ” Angered by his own daughter ' s betrayal , the king slew his daughter ( in a popular version of the tale he beheaded her ) . Then he jumped into the river with the giant golden turtle . Trọng Thủy , searching for his beloved wife , arrived a few minutes later at the scene . The body of his beloved wife was lying in a pool of blood and his father - in - law was nowhere to be seen . In accordance with conjugal fidelity and devotion , he drew his sword and killed himself as well , in order to be with his wife forever in eternity . The story of Mỵ Châu and Trọng Thủy is a tragic love story retold often in Vietnam ' s literature . Having defeated An Duong Vuong , Triệu Đà annexed the newly conquered territory to his own and created the state of Nam Viet ( Nanyue ) , proclaimed himself a new emperor of the Triệu Dynasty ( 207 – 111 BCE ) . Historians . Vietnamese historians typically view the main events of this era as having roots in historical fact . However interpretation and reconciliation of the history of the period has been set in , and sometimes against , the history of Soviet interpretation of history .