The Royal Records of the Nguyen Dynasty keeping as store at the National Archives Centre I under the State Archives and Collection Department consist of 773 tomes with more than 85,000 texts, including 16 units which relate to the management and execution of the sovereignty over Hoang Sa, Truong Sa Islands. In addition, there is one record sheet detected in Ly Son Island and one sheet contributed by historian Phan Thuan An Hue offering the Ministry of Foreign Affairs. Therefore, there are 19 explored and published royal record sheets in total. The author has studied carefully on them and came to have the conclusions. Prior to the Nguyen Dynasty, especially under the Gia Long and Minh Menh Kings, the tasks of managing and enforcing the sovereignty over the two Islands in the East Sea were upgraded in the national level under the Emperors' direct rules. The Nguyen Dynasty became aware that was essential area of water frontier which needed to be closely managed and used by naval forces as key factors associated with sea coastal laborers in Quang Ngai, especially in Ly Son Island. Fleets were sent out every two years to measure sea route, to map islands, to plant the sovereignty, trees, to build Buddhist temples, or collect sea produces or fortunes from wrecked ships. Those rich contents were reflected in the Royal Records which are the State letters with the Emperors' approvals and seals and the state agencies. These are the historical and legal evidences of highest values of a country under the centralized monarchical regime.