Karate began as a common fighting system known as te (Okinawan: ti) among the Pechin class of the Ryukyuans. After trade relationships were established with the Ming dynasty of China by King Satto of Chūzan in 1372, some forms of Chinese martial arts were introduced to the Ryukyu Islands by the visitors from China, particularly Fujian Province. A large group of Chinese families moved to Okinawa around 1392 for the purpose of cultural exchange, where they established the community of Kumemura and shared their knowledge of a wide variety of Chinese arts and sciences, including the Chinese martial arts. The political centralization of Okinawa by King Shō Hashi in 1429 and the policy of banning weapons by King Shō Shin in 1477, later enforced in Okinawa after the invasion by the Shimazu clan in 1609, are also factors that furthered the development of unarmed combat techniques in Okinawa.
This information, and more about Karate, can be found at the following Wikipedia link; http://en.wikipedia.org/wiki/Karate