Tong Dian (Comprehensive Institutions) by Du You (Tang Dynasty)

It is recorded in Tong Dian, a book written by Du You in the Tang Dynasty (AD 618-907) that, "Prior to the Xia, Shang and Zhou Dynasties, the region to the south of Wuling and the north of Zhanghai had been the desolate area. After Qin unified China, three prefectures including Nanhai were established there." "The desolate area" refers to the vicinities of the present Lingnan. "Since the Han Dynasty, exploitation of the area has been exercised." Records of the Chinese ancestors developing and utilizing the South China Sea are frequently seen in the subsequent classics.