[CareerSlamPova]

India-Pakistan

Obviously due to partition.

After partition, it was decided that some territories will go to Pakistan(the Muslim population ones) and some to India. The princely states could decide which country they want to join or remain independent. Kashmir was one of the princely states, which decided to join India. But Pakistan wanted Kashmir since it's population is dominated by the Muslims, so it wrongly acquired some parts of Kashmir(called PoK: Pakistan occupied Kashmir) and that resulted in a war(and more followed for the same.)