Kulin Brahmins are those Brahmins in Bengal who can trace themselves to the five families of Kanauj (Kanyakubja), Uttar Pradesh who migrated to Bengal.They were given immense power during the reign of the Sena/Sen kings who were staunch Hindus and did not encourage the practice of any other religion. The five brahmin families were differentiated by their gotras. The Kanaujiya/kanyakubj brahmins who settled in Bengal had the following gotras: (Shandilya, Bhardwaj, Kashyap, Swavarna and Vatsav/Vatsya); these gotras denote the Rishis whose followers the brahmins were.
Some of these kuleen families settled in Barendrabhoom and some in Rarhbhoom in what is present day Bangladesh. The descendants of these families became known as Rarhi and Barendra brahmins as per their settlement.
The common surnames of Rarhi brahmin family are (ranked equally):
The common surnames of Barendra brahmin family are (ranked equally):
Apart from these many others like Chakroborty, Bhattacharya, Ray/Roy, Roy Choudhury, Majumdar, etc., which are, indeed, titles conferred on certain privileged families from among the above mentioned surnames, could also be Kulin if they are Rarhi Brahmins. Khan and Chowdhury are titles awarded to many kuleen brahmin families because of their ancestral rule or profession.
The connection between the saraswat brahmins and kanaujiya/kanyakubj brahmins is this that during the Aryan migration the saraswat brahmins, called thus because they lived along the banks of the river saraswati, which began to disappear underground during Parushurama's time. These brahmins migrated to south, north and northwestern parts of the subcontinent.
Gaud Saraswat Brahmins The kashmiri pandits are of the same lineage as these saraswats and consider themselves to be pure Aryan because their descendants didn't mingle with the indigenous people. Those that settled in north India also went to what is present day Uttar Pradesh, where Kannauj is located From here they migrated to Gaud or Gour. From Gour, a small community comprising about seven families migrated to the South of the subcontinent.They were known as Gaud Saraswat Brahmins.
Kulin Pratha (Kulin System) was initiated by the Sena kings in Bengal whereby the kings gave land and power to the Brahmins to promote vedic principles in the society, leading to a strict and disciplined lifestyle. Simultaneously they also enforced strict rules on family and marriage rules on Brahmins, leading to the birth of Kulin Brahmins, an apex section/class/caste of the society. It was said that a person is Kulin if and only if all the 14 generations on his father's and mother's side were Kulin. This created a very problematic divide in the society. This was also opposed by many Brahmins. Yet it became a norm, probably because the kulin Brahmins got lured by the newly acquired power in the society.
Kulin Pratha was a very strict practice leading to many problems in Bengali society. If a daughter of a Kulin family doesn't wed in a Kulin family then the parent family loses their Kulin identity. These led to several problems like young girls getting married to old Kulin married men out of desperation of finding a Kulin groom. It was not uncommon for Kulin grooms to have several wives, most of which stayed at their parents home, just to be wed (for the sake of the ritual) to a Kulin and hence maintain their Kulin status.
Nowadays many Brahmins have shunned their Kulin identity and have mixed equally with all the Brahmins in Bengal and other parts of India. It is hard to state the current stand of these families on Kulin Pratha. It may surface during the marriage process, but the young are not concerned.
Marriages within the gotra ("swagotra" marriages) are banned under the rule of exogamy in the traditional matrimonial system. People within the gotra are regarded as kin and marrying such a person would be thought of as incest.
A much more common characteristic of south Indian Hindu society is permission for marriage between cross-cousins (children of brother and sister). Thus, a man is allowed to marry his maternal uncle's daughter or his paternal aunt's daughter, but is not allowed to marry his father's brother's daughter. She would be considered a parallel cousin who is treated as a sister.
According to strict Hindu tradition, the term gotra is used only for the lineages of Brahmin, Kshatriya and Vaishya varnas. Brahminical Gotra relates directly to the original seven "saptarishis" Rishis of the Vedas. Later, the term "gotra" was associated with broader meanings of any lineage, Brahmin or otherwise.
A common mistake is to consider gotra to be synonymous with clan or kula. A kula is basically a set of people following similar cultural rituals, often worshipping the same God (the Kula-Devata - the God of the clan). Kula has nothing to do with lineage or caste. In fact, it is possible to change one's kula, based on one's faith or Ishta-deva.
It is common practice in preparation for Hindu marriage to inquire about the Kula-Gotra (meaning Clan-Lineage) of the bride and bridegroom before approving the marriage. In almost all Hindu families, marriages within the same gotra are prohibited, since people with same gotra are considered to be siblings. But marriage within the kula is allowed and even preferred.