Complex sentence: Barun De (30 October 1932--16 July 2013) was an Indian historian, who studied 18th-and 19th century Indian social and economic history, the Bengal Renaissance, and British constitutional history.
Split into simpler sentences: Barun De (30 October 1932--16 July 2013) was an Indian historian. His specialisms were the social and economic history of India in the eighteenth and nineteenth centuries, the Bengal Renaissance, and British constitutional history.