The "partition" likely refers to the partition of British India into two separate independent nations: India and Pakistan, which occurred in August 1947. The primary cause of the nightmare that ensued after the partition was the communal violence and mass displacement of populations along religious lines, particularly between Hindus, Muslims, and Sikhs. The partition led to widespread riots, killings, and atrocities as millions of people migrated across the newly drawn borders to be with their religious communities. The lack of adequate preparation, the suddenness of the partition, and the communal tensions that had been simmering for years all contributed to the chaos and violence that followed, resulting in one of the largest and most tragic migrations in history.