The dividing of india into two nations was referred to as

Partition of India/Indian Partition

Explanation:

After the World War II ended, the European imperial powers were in ruins, economically badly damaged, and with depleted and exhausted military forces. This meant that they are no longer able to hold onto their colonies, so they had to grant them independence. India was one of those countries that was granted independence. And while that came as a big positive, there was also a negative in it, the country was divided on religious basis into two countries, the Hindu dominated India, and the Muslim dominated Pakistan. That resulted in lot of anger, tensions, and conflicts between the two groups and countries, with millions of people being displaced, injured, or murdered. It didn't stopped there though, as after the initial partition where there was suppose to be two countries, later it turned to be three, as Bangladesh managed to become a separate country too.

during world war ii