Shitō-ryū was founded by Kenwa Mabuni in the early 1930′s. Mabuni (1889–1952) had been learning martial arts since his childhood. Due to his talent and hard work, he quickly became a well known martial artist, achieving renown at the age of 13. Later, he learned karate from other schools and Chinese Qigong, integrating all the martial arts styles and creating his unique one. To honor his two teachers, he named his school “ Shitō-ryū ”.
Currently, Shitō-ryū karate is considered by some to be the best preserved and most complete karate style. It accords great importance to the cultivation of morality.
Along with Shotokan-Ryu, Wado-Ryu and Goju-Ryu, Shito-Ryu completes the four main branches of Karate. While there are lots of other lineages that have come into being during the development of Karate, these four are considered by many to be the pillars of the martial art.
Here’s a great video talking about the development of Shitō-ryū Karate. A little old and shot on Cam but it gives a lot of great information.