Jāti is the term traditionally used to describe a cohesive group of people in the Indian subcontinent, like a tribe, community, clan, sub-clan, or a religious sect. Each Jāti typically has an association with an occupation, geography or tribe. Different intrareligious beliefs (e.g. Vaishnavism or Smarthism or Shaivism) or linguistic groupings may also define some Jātis. The term is often translated approximately in English as caste.
A person's surname can reflect a community (Jāti) association: thus Gandhi = perfume seller, Dhobi = washerman, Srivastava = military scribe, etc.
A 2016 study based on the DNA analysis of unrelated Indians determined that endogamous Jatis originated during the Gupta Empire.
Professor Madhav Gadgil (1983) has described Jātis as self-governing, closed communities, based on his research in rural Maharashtra: Indian society is even today an agglomeration of numerous castes, tribes and religious communities. The tribal and caste groups are endogamous, reproductively isolated populations traditionally distributed over a restricted geographical range. The different caste populations, unlike tribes, have extensive geographical overlap and members of several castes generally constitute the complex village society.
In such a village society, each caste, traditionally self regulated by a caste council, used to lead a relatively autonomous existence. Each caste used to pursue a hereditarily prescribed occupation; this was particularly true of the artisan and service castes and the pastoral and nomadic castes. The several castes were linked to each other through a traditionally determined barter of services and produce (Ghurye 1961, Karve 1961).
These caste groups retained their identity even after conversion to Islam or Christianity. Each of the caste groups was thus the unit within which cultural and perhaps genetic evolution occurred, at least for the last 1500 years when the system was fully crystallized and probably much longer.