1 Jiaozhi (Giao Ch) in the Han Period Tongking Gulf Li Tana The Gulf of Tongking extends from the western side of the Leizhou Peninsula and the coast of present-day Guangxi to north and central Vietnam. This crescent naturally embraces Hainan Island’s west ern coast. Many harbours and islands dot the 130,000 kilometres 2 of the Gulf’s coastline. In a comparison of various sections of the entire mainland Southeast Asian coastline, the Gulf of Tongking first reached its current sea level more than 2000 years ago, while the coast of peninsular Thailand/Malaysia reached this level 500 years later. The coastline of Chao Phraya and the Mekong deltas formed last, and this region was still swampy and uninhabitable from between the tenth and fifteenth centuries BCE. 1 Today’s Hanoi area, also known as the Hanoi Valley, has a long history of settlement. 2 A principal difference between the prehistoric chronology of northern Vietnam and other parts of Southeast Asia is the presence of an early Neolithic, which it shared with western Guangxi. 3 This chapter introduces early Jiaozhi, a territorial unit covering the present day Red River plains, coastal Guangxi and western Guangdong, and discusses its importance in the exchange system of the Gulf of Tongking and South China Sea nearly two millennia ago. Contrary to conventional scholarship, which has stressed political forces pushing from north to south that resulted in Chinese colonisation of the Red River plain, this chapter examines early Jiaozhi in its own context, as a territorial expanse occupying the same horizontal line. It argues that, by eliminating the once powerful Nanyue (Southern Yue, based in Canton) kingdom in 111 BCE, the Han dynasty established Jiaozhi’s dominant trading position as both market and entrepot for goods brought by land and sea. Jiaozhi’s emergence as the jewel of the Han south highlights the importance of the Gulf of Tongking for the early Maritime Silk Road, as well as revealing the mutual interdependance of the region of modern Guangxi and the Red River plain so long ago.