The Koka and Iga schools are the most famous schools of the ninja arts but they are not the only ones. They say there were 49 schools of ninja in the territory of Japan.

All schools were created with the purpose of serving the(master lord) of their domain and worked for the development of the region. However, only the Koka and Iga schools were widely known.
The art and of ninja were not meant to be shown in public, and so there are almost no historical records, and no famous names. In the Sengoku period (1467-1603) when Kyoto was the capital of the country and military commanders (Shogun) Nobunaga, Hideyoshi, Ieyasu fought with each other, the Iga and Koka clan took part in the fight.