Samurai Suenaga facing Mongols, during the Mongol invasions of Japan . Moko Shurai Ekotoba (蒙古襲来絵詞), circa 1293. Various samurai clans struggled for power during the Kamakura and Ashikaga Shogunates . Zen Buddhism spread among the samurai in the 13th century and helped to shape their standards of conduct, particularly overcoming fear