The term jiuzhou can be dated back to as early as pre-Qin period (before 221 BCE) to refer to the entire China, divided into nine major regions. The exact locations of the nine regions vary from time to time. It largely overlaps with the habitation of Han Chinese people. Sihai were four bodies of water that metaphorically made up the boundaries of ancient China. There is a sea for each of the four cardinal directions. The West Sea is Qinghai Lake, the East Sea is the East China Sea, the North Sea is Lake Baikal, and the South Sea is the South China Sea. The lands “within the Four Seas,” a literary name for China, are alluded to in Chinese literature and poetry (Wikipedia 2023). So jiuzhou and sihai together the whole world—both within and outside the boundaries of China.
