What is "tamagusuku"

was a king of the Ryūkyū Islands.

Tamgusuku was a "king" of the Okinawan kingdom of Chūzan from roughly 1314-1336. He was the third son of Eiji (r. 1309-1313), he was the fourth ruler of the lineage of Eiso (r. 1260-1299).

Succeeding his father Eiji as paramount chief of Okinawa's territorial lords at the age of nineteen, Tamagusuku lacked the charisma and leadership skills to command respect and loyalty from those lords (the anji). A number of these lords rebelled, and the island of Okinawa came to be divided into three kingdoms. Tamagusuku, remaining in Urasoe, became king of Chūzan. His failure to institute reforms or innovations in governance is generally claimed as one of the causes of the fall of the lineage (dynasty), which ended with Tamagusuku's son and successor Seii.

The Lord of Ōzato fled south from Tamagusuku's capital at Urasoe and, along with his followers, formed the kingdom of Nanzan (南山, Southern Mountain).

The Lord of Nakijin, based some distance to the north, declared himself king of Hokuzan (北山, Northern Mountain).