“Dai Nam Nhat Thong Chi” is the official geographical book of the Nguyen dynasty compiled by Quoc Su Quan (Office of National History established in 1820 by King Minh Mang) from 1865 to 1910. The part dealing with Quang Ngai province determined that the Hoang Sa archipelago belonged to Quang Ngai province and the exploitation of the Hoang Sa continued and the management was boosted under the Gia Long and Minh Mang Kings.
“In the East of Quang Ngai province there is the sand island (it means Hoang Sa) with sandy beaches adjacent to the sea, used as the moat; in the Southwest of the highlands there were solid long ramparts, the South connecting to Binh Đinh there was Ben Da Pass blocking, in the North adjacent to Quang Nam province there was Sa Tho rapids as a boundary….
…. In the early time of King Gia Long, a Hoang Sa team was set up in accordance with the old custom, in early time of King Minh Mang, public boats were often sent to explore the sea route, having found a white sand bank with the circuit of 1,070 truong (one truong equals 10 metres) with green foliage all around, in the middle of the sandbank there was a well, in the Southwest, there was an ancient temple with unknown construction time, but it had a stele inscribed 4 words “Van Ly Ba Binh” (Thousands of miles with quiet waves). This sandbank was formerly called Phat Tu Son, in the East and the West of the island there were coral reefs with a 340-truong large sandbank coming to the surface called Ban Than Thach. In the year of Minh Mang the 16th, the king sent public boats to carry bricks and stones to build a temple and plant a stele there on the left of the temple to mark and put the tree seeds on the right, the left and behind the temple. While building the temple, the workers had found copper leaves and iron of 2,000 kilos in weight”.