Complex sentence: In 1971, when East Pakistan Later named as Bangladesh got apart from Pakistan because of Zulfiqar Ali Bhutto who wanted to came in power in West Pakistan Saieen GM Syed began to demand self-determination for the people of Sindh.
Split into simpler sentences: In 1971, when East Pakistan (now Bangladesh) seceded from Pakistan at the behest of Zulfiqar Ali Bhutto who wanted to come in power in West Pakistan. Saieen G.M. Syed began to demand self-determination for the people of Sindh.