Complex sentence: The Bengal Army of the East India Company was mainly recruited from high castes living in Bihar and the Awadh, especially Bihari Rajputs and Bhumihars who were referred to as "Purbiyas".
Split into simpler sentences: The Bengal Army of the East India Company was mainly recruited from high castes living in Bihar and the Awadh. Especially Bihari Rajputs and Bhumihars who were referred to as "Purbiyas".