Even after the battle for independence from Britain, life still wasn't easy for the people of the old British India. When the famous fight led by Gandhi ended, the area was divided according to the religion of the majority of people in each region, resulting in Pakistan, with mostly Muslims (divided in East and West) and India, which had more Hindus.
However, this division did not bring happiness and peace like the men in charge originally predicted. At the time the Partition was idealized, they did not know what it would require, having many unforeseen consequences.
The Partition brought a lot of violence (even though a war between the countries hadn't begun yet) within people of different religions, since they were very attached to their territories and devoted to their faith. Even so, in hope to scape shootings and mass casualties and to have a better life, Muslims started to go to Pakistan, while Hindus and some minorities, like Sikhs, went to India, resulting in 15 million people migrating, a number that exceeded the leader's predictions. Unfortunately, while moving, violence was still present, and deceases started to spread in refugee camps. Transport to leave the country wasn't good either: the ones who did not want to walk huge distances had to go with trains, which were always packed, like we can see in TV shows such as Ms. Marvel. Another thing the leaders did not predict was how homogeneous West Pakistan became, having over 95% of Muslim population. This brought fear to Pakistan's politicians, considering that they wanted to have a significant Muslim population to still have some influence in India, but they remained the largest minority there, being almost 10% of the country.
The conflict got even worse after these countries entered in war because of two regions: Jammu and Kashmir. The territories belonged to India; however, the majority of the population was Muslim, resulting in a conflict, which started in October 1947 and finished in July 1949 thanks to UN's intervention, splitting the region. Two other brief wars started in 1965 and 1999 because of these areas, which still remain an interest to both countries that got a new adversary: China is claiming that part of Kashmir should belong to it.
Between these wars, in 1971, East Pakistan became Bangladesh and the situation looks better now, considering that there hasn't been a direct conflict since then. However, these countries are armed with nuclear weapons, therefore another war could bring terrible consequences.