ABSTRACT
The Portuguese had established a trading post in Macau since 1511 and turned Macau into a colony in 1557. From that time, the Western merchant ships traversed the East Sea more frequently, and Portuguese navigators began to explore the area, including the Paracel archipelago. Besides, the Portuguese also had very old and rare maps, produced in the mid-sixteenth century, with indications of the Paracel archipelago. Vietnamese and Western maps, and pre-1909 Chinese maps showing Hainan Island as the southernmost point of China, were clear proofs of Vietnam's sovereignty over Paracel and Spratly archipelagos. Under Emperor Gia Long, Pham Quang Anh, a member of the Hoang Sa team, was ordered to go to the Paracel archipelago to carry out the survey and to make marine hydrological measurements. Although the surveying and map drawing of the Paracel archipelago in the time of the Nguyen Dynasty was much more thorough, they were relatively backward when compared to Western advanced mapping techniques.
