Karate developed in the Ryukyu Kingdom prior to its 19th-century annexation by Japan. It was brought to the Japanese mainland in the early 20th century during a time of cultural exchanges between the Japanese and the Ryukyuans. In 1922 the Japanese Ministry of Education invited Gichin Funakoshi to Tokyo to give a karate demonstration. In 1924 Keio University established the first university karate club in Japan and by 1932, all major Japanese universities had karate clubs. After the Second World War, Okinawa became an important United States military site and karate became popular among servicemen stationed here. The martial arts movies of the 1960s and 1970s served to greatly increase its popularity and the word karate began to be used in a generic way to refer to all striking-based Oriental martial arts. Karate schools began appearing across the world, catering to those with casual interest as well as those seeking a deeper study of the art.