Complex sentence: Another reason for popular settlement is the pharmaceutical companies existing on Long Island, New York; there are quite a large number of Bangladeshi-owned pharmaceutical companies in Nassau County and Suffolk County on Long Island employing many people of Bangladeshi origin.
Split into simpler sentences: Another reason for popular settlement are the pharmaceutical companies existing on Long Island, New York. There are quite a large number of Bangladeshi-owned pharmaceutical companies in Nassau County and Suffolk County on Long Island employing many people of Bangladeshi origin.