Over the next century and a half, however, a revolution began, as Zen at first gradually and then precipitously became the preoccupation of Japan's ruling class. The Zen explosion came about via a combination of circumstances. We have seen that the warrior ruler Hojo Tokiyori (1227- 63) was interested in the school and offered Dogen a temple in Kamakura, an invitation Dogen refused. However, in 1246 an emigre Ch'an master from the Chinese mainland named Lan-ch'i (1212-78) appeared in Japan uninvited, having heard of Japanese interest in Ch'an. He went first to Kyoto, where he found Zen still subject to hostile sectarianism, and then to Kamakura, where he managed in 1249 to meet Tokiyori. The Japanese strongman was delighted and proceeded to have the temple of another sect converted to a Zen establishment, making Lan-ch'i abbot. Shortly after, Tokiyori completed construction of a Sung-style Zen monastery in Kamakura, again putting Lan-ch'i in charge. This Chinese monk, merely one of many in his native China, had become head of the leading Zen temple in Japan. When word got back, a host of enterprising Chinese clerics began pouring into the island nation seeking their fortune.2 Thus began the next phase of early Japanese Zen, fueled by the invasion of Chinese Ch'an monks. This movement occupied the remainder of the thirteenth century and was spurred along by unsettled conditions in China--namely the imminent fall of the Southern Sung Dynasty to the Mongols and a concurrent power struggle within Ch'an itself, which induced monks from the less powerful establishments to seek greener pastures.3 In 1263 a senior Ch'an cleric named Wu-an (1197-1276) arrived in Kamakura and was also made an abbot by Tokiyori.4 The first monk, Lan-ch'i, thereupon moved to Kyoto and began proselytizing in the old capital. Wu-an subsequently certified Tokiyori with a seal of enlightenment, making the military strongman of Japan an acknowledged Ch'an master. Tokiyori's interest in Zen did not go unnoticed by the warriors around him, and his advocacy, combined with the influx of Chinese monks appearing to teach, initiated the Zen bandwagon in Kamakura.