Provinces of Japan (令制国, Ryōseikoku) were first-level administrative divisions of Japan from the 600s to 1868.
Provinces were established in Japan in the late 7th century under the Ritsuryō law system that formed the first central government. Each province was divided into districts (郡, gun) and grouped into one of the geographic regions or circuits known as the Gokishichidō (Five Home Provinces and Seven Circuits). Provincial borders often changed until the end of the Nara period (710 to 794), but remained unchanged from the Heian period (794 to 1185) until the Edo period (1603 to 1868). The provinces coexisted with the han (domain) system, the personal estates of feudal lords and warriors, and became secondary to the domains in the late Muromachi period (1336 to 1573).