The Sadh is one of the few endogamous religion. They call the God in the name Satnam, which means "the true name". Their customs and traditions are similar to Hinduism from where most of the members are recruited. Their population is mainly concentrated in Uttar Pradesh, Uttrakhand, Haryana, Rajasthan and Punjab. It is one of the richest caste in India.
The Collaborative International Dictionary
Sadh \Sadh\, n. [Skr. s[=a]dhu perfect, pure.]
A member of a monotheistic sect of Hindoos. Sadhs resemble
the Quakers in many respects.
--Balfour (Cyc. of India).