What is "chuzan"

Chūzan (中山) was one of three kingdoms which controlled Okinawa in the 14th century. Okinawa, previously controlled by a number of local chieftains or lords, loosely bound by a paramount chieftain or king of the entire island, split into these three more solidly defined kingdoms within a few years after 1314; the Sanzan period thus began, and would end roughly one hundred years later, when Chūzan's King Shō Hashi conquered Hokuzan in 1419 and Nanzan in 1429.

The united Okinawan state was called the Ryūkyū Kingdom, but would continue to be referred to as "Chūzan" in various official documents of the Ryukyuan royal government, and those of many other states in the region.