One of the earliest evidence of Bhuyans in Mlechchha dynasty during the 9th century reign of Balavarman III by using 'parcelization' of power.

[2] Historical record of Raut-Kuchi grant (1329 A.D.) shows that western Brahmaputra valley comes from Adi-Bhuiyan group's Purushottam Dasa's grandfather Basudeva, who was a minister of Kamata king Indranarayan, who commanded a thousand men and war elephants.

[6][7] Mughal histories, mainly the Akbarnama, the Ain-i-Akbari and the Baharistan-i-Ghaibi refers to the low-lying regions of Bengal as Bhati[2].

[2] Keeping in view the theatre of warfare between the Bara-Bhuiyans and the Mughals, the Baharistan-i-Ghaibi mentions the limits of the area bounded by the Ichamati River in the west, the Ganges in the south, the Tripura to the east; Alapsingh pargana (in present Mymensingh District) and Baniachong in the north.

[2] The Bara-Bhuiyans rose to power in this region and put up resistance to the Mughals, until Islam Khan Chisti made them submit in the reign of Jahangir.