In 794 Emperor Kanmu moved the capital from Nagaoka-kyō to Heian-kyō in Kadono district of Yamashiro Province. Following the assassination of Fujiwara no Tanetsugu and the vengeful spirit legends surrounding Prince Sawara at Nagaoka, Wake no Kiyomaro and others advocated for a new capital. Modeled on Chang'an, the grid city of roughly 5.2 km north–south and 4.5 km east–west became Japan's imperial capital for nearly 1,100 years and ushered in the Heian period.