 In fact, there is a record in Chinese literature that a king of Japan sent a letter in 478 to ask the Chinese emperor's approval for employing three ministries.In addition, remains of the Korokan (, Government Guest House) were found in Fukuoka underneath a part of the ruins of Fukuoka Castle.Kublai Khan of the Mongol Empire turned his attention towards Japan starting in 1268, exerting a new external pressure on Japan with which it had no experience.