Kamakura Period During this period, the Feudal system was established by Minamoto Yoritomo. Yoritomo's military government was called the Kamakura Shogunate which is what this period was named after. After he defeated his family rival, the Taira family, Yoritomo built his own military administration (Bakufu) to fight beside the imperial court. He officially became shogun in 1192 when his authority was given imperial approval. The Hojo family became regents for the Shogunate and wielded power in the (jun 30, 1185