Many subcastes of Bania have subcastes known as Bisa or Dasa, that is 'Twenty' or 'Ten' groups, the former being of pure descent or twenty-carat, as it were, and the latter the offspring of remarried widows or other illicit unions.

In the course of some generations such mixed groups frequently regain full status in the caste.
Subcastes are also formed from members of other castes who have taken to the occupation of the caste in question and become amalgamated with it; thus the Korchamars are Koris (weavers) adopted into the Chamar (tanner) caste; Khatri Chhipas are Khatris who have become dyers and printers; the small Dangri caste has subcastes called Teli, Kalar and Kunbi, apparently consisting of members of those castes who have become Dangris; the Baman Darzis or tailors will not take food from any one except Brahmans and may perhaps be derived from them, and the Kaith Darzis may be Kayasths; and so on.
Occasionally subcastes may be formed from differences of religious belief or sectarian practice.

In northern India even such leading Hindu castes as Rajputs and Jats have large Muhammadan branches, who as a rule do not intermarry with Hindus.

The ordinary Hindu sects seldom, however, operate as a bar to marriage, Hinduism being tolerant of all forms of religious belief.

Those Chamars of Chhattisgarh who have embraced the doctrines of the Satnami reforming sect form a separate endogamous subcaste, and sometimes the members of the Kabirpanthi sect within a caste marry among themselves.
Statistics of the subcastes are not available, but their numbers are very extensive in proportion to the population, and even in the same subcaste the members living within a comparatively small local area often marry among themselves and attend exclusively at their own caste feasts, though in the case of educated and well-to-do Hindus the construction of railways has modified this rule and connections are kept up between distant groups of relatives.