According to Tej Ram Sharma, an Indian historian, the office of Kayastha in Bengal was instituted before the Gupta period (c. 320 to 550 CE), although there is no reference to Kayastha as a caste at that time. He says some scholars have noted that:
Originally the professions of Kayastha (scribe) and Vaidya (physician) were not restricted and could be followed by people from different varnas including the brahmanas. So there is every probability that a number of brahmana families were mixed up with members of other varnas in forming the present Kayastha and Vaidya communities of Bengal.
Historians P. C. Choudhuri, K. R. Medhi and K. L. Barua are of the opinion that "the Brahmins noted in the Nidhanpur and Dubi inscriptions of king Bhaskaravarman", who bore surnames "which are at present used by Kayasthas of Bengal and Nagara Brahmins of Gujarat, were either of the Alpine origin or pre-Vedic Aryans", and similarly the Kayasthas and Kalitas of Assam "are also supposed to be descendants of extra-Vedic Aryans".
According to André Wink, another historian, the caste is first referred to around the 5th or 6th century CE and may well have become so identified during the period of the Sena dynasty. Between that time and the 11th-12th century this category of officials or scribes was composed of "putative" Kshatriyas and, "for the larger majority", Brahmins, who retained their caste identity or became Buddhists. As in South India, the Bengal region did not adhere to the four-fold varna system of Vedic Hinduism and instead comprised two groups, the Brahmins and the Shudras.
Sekhar Bandyopadhyay also places their emergence as a caste after the Gupta period. Referring to the linkages between class and caste in Bengal, he mentions that the Kayasthas along with the Brahmins and Baidyas, refrained from physical labour but controlled land, and as such represented "the three traditional higher castes of Bengal". Eaton mentions that the Kayasthas continued as the "dominant landholding caste" even after the Muslim conquests on the Indian subcontinent, and absorbed the descendants of the region's old Hindu rulers. The Pala, Sena, Chandra, and Varman dynasties and their descendants, which claimed the status of Kshatriya, "almost imperceptibly merged" into this caste, which in this way became "the region's surrogate Kshatriya or warrior class". Wink says that they "also ranked as shudras". Professor Julius J. Lipner mentions that the caste status of the Bengali Kayasthas is disputed and says that while some authorities consider that they "do not belong to the twice-born orders, being placed high up among the Shudras; for other authorities they are on a level with Kshatriyas, and are accorded twice-born status."
In Bengal between 1500 and 1850 CE, the Kayasthas were regarded as one of the highest of Hindu castes in the region.
Kulin Kayastha and Maulika Kayastha
According to Ronald Inden, an Indologist, "many of the higher castes of India have historically been organised into ranked clans or lineages". The Bengali Kayastha was organised into smaller subcastes and even smaller ranked grades of clans (kulas) around 1500 CE. The four major subcastes were Daksina-radhi, Vangaja, Uttara-radhi and Varendra. The Daksina-radhi and Vangaja subcastes were further divided into Kulina or Kulin ("high clan rank") and Maulika or Maulik, the lower clan rank. The Maulika had four further "ranked grades". The Uttara-radhi and Varendra used the terms "Siddha", "Sadhya", "Kasta" and "Amulaja" to designate the grades in their subcastes.
Kulin Kayasthas have an associated myth of origin stating that five Kayasthas accompanied the Brahmins from Kannauj who had been invited to Bengal by the mythological king Adisur. Multiple versions of this legend exist, all considered by historians to be myth or folklore lacking historical authenticity. According to Swarupa Gupta this legend was
...fitted into a quasi-historical, sociological narrative of Bengal and deployed to explain the realities of caste and sub-caste origins and connections during the late nineteenth and early twentieth century.
- Sharma (1978), p. 115
- S. R. Bakshi; S. R. Sharma; S. Gajrani (1998). "Land and the People". Contemporary Political Leadership in India. APH Publishing Corporation. pp. 13–14. ISBN 81-7648-008-8.
- Wink (1991), p. 269
- Bandyopadhyay, Sekhar (2004). Caste, Culture, and Hegemony: Social Dominance in Colonial Bengal. Sage Publications. p. 20. ISBN 81-7829-316-1.
- Eaton (1996), p. 102
- Lipner, Julius J. (2009). Debi Chaudhurani, or The Wife Who Came Home. Oxford University Press. p. 172. ISBN 978-0-19973-824-3.
- Inden (1976), p. 1
- Inden (1976), p. 34
- Inden (1976), p. 1-2
- Sengupta (2001), p. 25
- Gupta (2009), pp. 103-104
- Hopkins (1989), pp. 35-36
- Eaton, Richard Maxwell (1996), The Rise of Islam and the Bengal Frontier, 1204-1760, University of California Press, ISBN 978-0-52020-507-9
- Gupta, Swarupa (2009), Notions of Nationhood in Bengal: Perspectives on Samaj, C. 1867-1905, Brill, ISBN 978-9-004-17614-0
- Hopkins, Thomas J. (1989), "The Social and Religious Background for Transmission of Gaudiya Vaisnavism to the West", in Bromley, David G.; Shinn, Larry D., Krishna consciousness in the West, Bucknell University Press, ISBN 978-0-83875-144-2
- Inden, Ronald B. (1976), Marriage and Rank in Bengali Culture: A History of Caste and Clan in Middle Period Bengal, University of California Press, ISBN 978-0-520-02569-1
- Sengupta, Nitish K. (2001), History of the Bengali-Speaking People, UBS Publishers' Distributors, ISBN 81-7476-355-4
- Sharma, Tej Ram (1978), Personal and Geographical Names in the Gupta Inscriptions, New Delhi: Concept Publishing Company
- Wink, Andre (1991), Al-Hind, the Making of the Indo-Islamic World, Volume 1, Brill Academic Publishers, ISBN 978-9-00409-509-0