[3] He was best known for his works on medieval and early modern Bangladeshi and South Asian history.
His dissertation topic was Social History of the Muslims in Bengal.
He completed a second PhD from the School of Oriental and African Studies, University of London.
In 1966, he joined Chittagong University as chairman of the Department of History.
He joined the Institute for Bangladesh Studies of the University of Rajshahi as a senior fellow and in 2001 was made professor emeritus.