Complex sentence: Some Biharis collaborated with the Pakistan Army in committing atrocities against the Bengalis during the war, and in return, Biharis faced numerous reprisal attacks from Bengali mobs and militias.
Split into simpler sentences: Some Biharis collaborated with the Pakistan Army in committing atrocities against the Bengalis during the war. In return, Biharis faced numerous reprisal attacks from Bengali mobs and militias.