Dewa Sanzan (出羽三山, "three mountains of Dewa") are three sacred mountains in Yamagata Prefecture, each with a shrine on or near its peak. The mountains are named Haguro-san, Gas-san and Yudono-san and remain centers of mountain worship. Representing birth (Haguro-san), death (Gas-san) and rebirth (Yudono-san), the mountains are usually visited in that order.
Dewa Sanzan is a center of Shugendo, a folk religion based on mountain worship, blending Buddhist and Shinto traditions. Shugendo practitioners, called yamabushi, perform feats of endurance as a means of transcending the physical world. Training includes such tasks as long pilgrimages and endurance of the elements.
Evidence of Shugendo's most extreme test of physical endurance and religious devotion lies in the nearby Churenji and Dainichibo temples, where two monks succeeded in preserving their own bodies as mummies through extreme diet modification and meditation. Although the practice is now banned, these self-mummified monks are considered Buddhas.
Part of Dewa Sanzan's appeal is its remoteness. Yamagata's heavy snowfall makes travel in the mountains difficult during the winter when only Haguro-san remains open. The best time to visit is between July and mid September when all three shrines are open.