Samurai in japan pm By _s05823 400 Horses were introduced into Japanese fighting. Horses introduced into Japanese fighting. Period: 400 to Dec 31, 1876 Samurai 500 Buddhism became a powerful philosophy for the samurai Jan 1, 1192 Yoritomo became first permanent shogun Sep 1, 1200 Samurai defeated Mongols Jan 1, 1542 Guns introduced Jan 1, 1876 New law ended samurai's right to use swords