> They separated from West Pakistan on the basis of their Bengali Identity
This is not true. People in the Indian state of West Bengal also speak Bengali and have a Bengali identity. The split of Bengal into West Bengal and Bangladesh was based on religion.
I am talking about the split between West Pakistan and East Pakistan (Bangladesh). My point is that the Idea that Pakistan could be a united country based on a common religion failed based on the fact that the Bengalis found their Bengali identity more important than their religious identity.
That's not why it failed. It failed because we had an extremely stupid military dictator with racist tendencies that carried out brutal massacres there.