Gichin Funakoshi, the founder of Shotokan karate, is generally credited with having introduced and popularized karate on the main islands of Japan. In addition, many Okinawans were actively teaching, and are thus also responsible for the development of karate on the main islands. Funakoshi was a student of both Asato Ankō and Itosu Ankō (who had worked to introduce karate to the Okinawa Prefectural School System in 1902). During this time period, prominent teachers who also influenced the spread of karate in Japan included Kenwa Mabuni, Chōjun Miyagi, Chōki Motobu, Kanken Tōyama, and Kanbun Uechi. This was a turbulent period in the history of the region. It includes Japan's annexation of the Okinawan island group in 1872, the First Sino-Japanese War (1894–1895), the Russo-Japanese War (1904–1905), the annexation of Korea, and the rise of Japanese militarism (1905–1945).