In the earliest centuries of Buddhism, monks were itinerant, wandering for nine months of the year. When the monsoons began, in July, they gathered together for teaching, instruction, meditation and encouragement. Theravada Buddhism, which is in the area of the monsoons, still keeps the rain retreats, even though its monks have long ago ceased to wander.
RAIN RETREAT
Meaning of RAIN RETREAT in English
Buddhism English glossary. Английский глоссарий буддизма. 2012