A Genocide That Led To The Creation Of A Country _ 1971 Bangladesh Genocide

Do you know which is the largest genocide since the Holocaust? Did you know that the Pakistani Army and pro-Pakistani Islamic Militants killed between 300,000 and 3,000,000 people and raped between 200,000 and 400,000 women in Bangladesh ? (then East Pakistan)

It's not your fault if you didn't know that, because it's not even recognized by the UN. Why was it downplayed so much? What happened? Why Bangladesh Separated from Pakistan? Why East Pakistan became Bangladesh?