The Three Mountains of Dewa (出羽三山, Dewa Sanzan) refer to the three sacred mountains of Mount Haguro, Mount Gassan and Mount Yudono, which are clustered together in the ancient province of Dewa (modern-day Yamagata Prefecture). Holy to the Japanese Shinto religion and especially the mountain ascetic cult of Shugendo, Dewa Sanzan are a popular pilgrimage site visited by many, including famed haiku poet Matsuo Bashō.
The Haguro Five-story Pagoda is a recognised national treasure of Japan.
Yamagata Prefecture (山形県, Yamagata-ken) is a prefecture of Japan located in the Tōhoku region of Honshu. It has a population of 1,005,926 (1 February 2025) and an area of 9,325 km (3,600 sq mi). Its neighbours are Akita Prefecture to the north, Miyagi Prefecture to the east, Fukushima Prefecture to the south, and Niigata Prefecture to the southwest.
The capital and largest city is Yamagata, with other major cities being Tsuruoka, Sakata and Yonezawa. The prefecture is located on Japan's western Sea of Japan coast and its borders with neighboring prefectures are formed by various mountain ranges, with 17% of its total land area being designated as Natural Parks. Yamagata Prefecture formed the southern half of the historic Dewa Province with Akita Prefecture and is home to the Three Mountains of Dewa, which includes the Haguro Five-story Pagoda, a recognised National Treasure of Japan.