Purkayastha is not a surname, it is a title for rulers or
administrators. 'Pur' means city/town/kingdom and 'Kayastha'
meaning ruler or administrator. There are many Vaidik/Srotriya
Brahmins from Sylhet district (currently in Bangladesh) of
undivided Bengal who received the Purkayastha title. There are also
many Kshatriyas or upper caste Kayastha of Bengal use this title as
well.