The founder of Kyokushin, Sosai Masutatsu Oyama, was born on 27 July, 1923. In 1953, Sosai Oyama opened his own karate dojo, named "Oyama Dojo," in Tokyo. In 1964,Sosai Oyama moved the dojo into the building that would from then on serve as the kyokushin world headquarters. In conjuction with this he also founded the "International karate organization kyokushinkaikan" to organize the many schools that were by then teaching the kyokushin style.
Kyokushin karate, under the leadership of Sosai Masutatsu Oyama, grew immensely and was considered to be the strongest karate in the world. Upon Sosai Oyama's death, in April 1994, the International Karate Organization (IKO) splintered into several groups.
There are several other groups that have formed for the purpose of teaching the kyokushin style without using the name IKO.
Kyokushin Budo Kai (KBK) .