Buzen Province was a province of Japan in the area of northeastern Kyūshū, corresponding to part of southeastern Fukuoka Prefecture and northwestern Ōita Prefecture. Buzen bordered on Bungo to the south, and Chikuzen to the north and west. Its abbreviated form name was Hōshū (豊州), although it was also called Nihō (二豊). In terms of the Gokishichidō system, Buzen was one of the provinces of the Saikaidō circuit. Under the Engishiki classification system, Buzen was ranked as one of the "superior countries" (上国) in terms of importance, and one of the "far countries" (遠国) in terms of distance from the capital.

Kyūshū is the third-largest island of Japan's four main islands and the most southerly of the four largest islands. In the past, it has been known as Kyūkoku , Chinzei and Tsukushi-no-shima . The historical regional name Saikaidō referred to Kyushu and its surrounding islands. Kyushu has a land area of 36,782 square kilometres (14,202 sq mi) and a population of 14,311,224 in 2018.