Bose or Basu or Boshu ( Bengali: do ) It is a surname found among Hindu Bengalis.You boses belong to Kayastha caste in Bengal. The bengali k yasthas evolved as a caste of a category of officials or scribes, between the 1st century and 5th/6th 11th/12th century AD, their components are putative Kshatriyas and mostly brahmans. [1] Boses are considered Kulin k yasthas, together with Ghoshes and Mithras.