Okinawa is a prefecture of Japan. Think of a prefecture as something similar to a state. Okinawa wasn't always part of Japan. It was it's own country and then became part of Japan twice. Once in 1609 when Japan invaded, and again in 1972 it became part of Japan again. Many people don't know this but Okinawa was actually under administration of the United States from 1945-1972 (because of WWII).
Okinawa is a subtropical island, meaning that it's usually much warmer than in other parts of the world. Most of the year it is hot and humid by our standards. Sensei Hayes once said, "Okinawa has the perfect weather for training, if you like high humidity."
Two of the major cities in Okinawa are Shuri and Naha. Both cities have been capitol of Okinawa at various times in history. The type of Shorin Ryu we practice comes primarily from Shuri.
Okinawa was a trading post between Japan and China for a very long time and this is reflected in the culture. There are influences from both Chinese and Japanese culture in addition to aspects of culture that are purely Okinawan.
America's first big involvement with Okinawa happened in WWII during the Battle of Okinawa. More on that in another post.