Many centuries ago there was a chain of small islands known as Ryu Kyu located off the Japanese mainland. The natives of Ryu Kyu practiced an unarmed fighting style known simply as 'te' meaning 'hand'. Ryu Kyu now known as Okinawa was one day invaded by the Japanese and the Okinawans had become prisoners in their own land. They were oppressed by their conquerors who had also banned them from using weapons.
The Japanese soldiers murdered and plundered to their own liking, and in time the shy and once peaceful Okinawans, many being merchants and farmers, started seeking a means to defend themselves.
Roughly around the 14th century, trade relations were established with China allowing Chinese merchants to come to Ryu Kyu and naturally some of them brought across their own Chinese martial arts. The native fighting art of 'te' eventually became meshed with Chinese arts and was secretly used in self defence against the soldiers. The Okinawans soon became very skilful and also quite clever in disguising this new 'okinawa-te' or 'Okinawan Hand'. They would practice in secrecy and disguised their killing techniques in a patterns of movement that looked like dance to the invaders(known as kata).
They even made use of farming tools and little known Chinese 'devices' as weapons that the soldiers couldn't detect. The Okinawans fought for their survival, never being as well equipped, paid or armed as the Japanese soldiers but still winning many small battles in self defence. For example the farmer who might defeat two soldiers assaulting his wife, or a teenage boy defeating an armed soldier who was attacking him. Early styles of okinawa-te were often generalized as Shuri-te, Naha-te, and Tomari-te, named after the three cities from which they emerged. Each area and its teachers had particular kata(pre-arranged dance-like movements simulating combat), techniques, and principles that distinguished their local version of te from the others. In time Japan and Okinawa become united and the once secretive okinawa-te, now known as karate(open hand) emerged from the shadows.
Fast forward to the beginning of the 20th century. The Japanese government demanded that the practitioners of all martial arts name and register their styles. Some now famous Okinawans such as Gichin Funakoshi(founder of the Shotokan style of karate) and Kenwa Mabuni(founder of the Shito Ryu style of karate) left Okinawa for the Japanese mainland with the goal of spreading karate and gaining public acceptance. In time and after many years of hard work by such Okinawans masters Karate gained popularity in Japan.
Today karate is the most famous martial art on the planet and means a lot of different things to many different people, from sport to discipline to spirituality. However, they should all remember how this legendary fighting style ever came into existence. Through the need for the weak to defend themselves!