Southerners feared it would lead to the end of slavery.
Answer:
YES. Absolutely. It was Zulfiqar Ali Bhutto and Yayha Khan, both equally responsible as well as majority of Sindhis, Punjabis and Pashtuns.
Punjabis, Pashtuns and Sindhis considered Bengalis inferior and never wanted a Bengali as PM. Due to Bengalis in majority numbers these people feared that if we didn't take action now, Bengalis might win every election and stay in power. Therefore there was a martial law and Army/Gov altogether got rid of Bengalis. Luckily, India helped and Bengalis got independence.
Since than Punjabis have majority. Punjabis stayed in power. The sad part is Bengali leader Mujib was NOT racist. He was well-educated and wanted to make Pakistan a great nation. Jinnah was “urdu speaking” but still created Pakistan Despite knowing that Urdu speaking will be a minority in Pakistan. Because Jinnah was also not racist and wanted a one single United nation for all Muslims (Sindhi, Punjabi, Balochi, Bengalis) Sadly, Jinnah was wrong. Right after Jinnah died there had been lots of discrimination, genocide. Minorities are being discriminated.
Balochi, Bengalis, Urdu speaking all have suffered so much because of Jinnah's decision. Many Sindhis are being discriminated. Due to these racist backward ignorant incomplete leaders Pakistan has become a failed nation and a backward shthole. 23 million paki kids don't attend school. 55 millions live below poverty line. The list goes on.
