The scenario described pertains to the partition of India in 1947, which resulted in a significant displacement of individuals due to the political changes and communal violence. Given that the migration was not voluntary but rather a result of political decisions and the subsequent chaos that followed, the most accurate classification of this migration is:
forced political migration
This is because the migration was driven by political factors (the end of colonial rule and the partition itself) and the resulting instability, rather than being motivated by environmental or purely economic reasons.