How did bath houses become popular

Bathing and concepts of cleanliness are not universal across societies. Cleanliness, for some, meant multiple times during a day bathing, while for others it may simply have a religious or spiritual significance, even while little bathing took place on a day-to-day schedule. For most of human history, private bath facilities were a rare commodity. Thus, it is the history of bath houses that is associated with social concepts of cleanliness and this was spread by factors that included empires, new religious/spiritual ideas, and other cultural influence.