The document discusses the advent of Islam in Bengal through various means:
1) Arab traders brought Islam to the Bengal coast as early as the 8th century through maritime trade.
2) The Muslim conquest of Bengal began in the 13th century when Turkic armies invaded and established rule over the region.
3) Sufi preachers greatly contributed to the spread of Islam by establishing khanqahs (Sufi centers) and missionary activities that attracted converts.
4) Lower caste Hindus and Buddhists converted to Islam to escape social inequalities, while some upper caste Hindus also converted through marriage or ideological attraction to Islamic ideals.