Mount Tanzawa Oyama can be seen from anywhere in the Kanto area, just like Mount Fuji, and has been revered by the Japanese since ancient times as a special mountain filled with mystery. Due to steam from Sagami Bay, the mountain was always covered with rain clouds, even when the weather was fine nearby, giving rise to the mountain's other name, Amefuri-Yama, which in turn became Afuri-Yama (Mt. Rainfall), and to the mountain's cult of "making rain". Ritual sites and pottery from the Jomon period have been found on top of Mt. Oyama, suggesting that the mountain was an object of veneration at least from that time.
This veneration reached its peak in the Edo period (1603-1867), when the "Ryo-mairi" (pilgrimage to the two mountains) became popular, with pilgrims making the pilgrimage with Mount Fuji. It is said that the annual number of climbers reached 200,000 while the population of Edo was one million, which shows the extent of the fervour.