Emperor Kanmu was the 50th emperor of Japan, reigning from 781 to 806 AD. He is known for moving the capital from Nara to Kyoto, which became the center of Japanese culture and politics for centuries. His reign marked the beginning of the Heian period, a time of significant cultural development. Kanmu implemented various reforms to strengthen the imperial government and reduce the power of the nobility and Buddhist temples. He promoted the use of the Chinese writing system and encouraged the arts, leading to advancements in literature and architecture during his rule.