Disclaimer, as an American the viewpoint here is from someone born and raised in the United States and thus my understand as be formed from limited exposure. I have travelled to Chennai often for work in the fin-tech sector.
The British Empire and Indian Subcontinent
From 1885 – 1937 British Indian Empire included the territory of the present nation states of Burma, Bangladesh, India, and Pakistan. Like many colonies in Asia, change was precipitated by local and national uprisings and their colonial rulers. We will ignore the long and arduous listing of battles between local forces and Britain and go to the results.
Burma (Myanmar) and WWII
The first partition of India of cleaved Burma (now Myanmar) off into its own colony. It happened in 1937, which was just as Japan began conquering every large territory in Asia. Burma was critical as a protector of sea-lanes between India and China. Although the coming war seems to have been the reason for the partition of Burma, many Burmese at the time believed it was to avoid giving Burma the new freedoms giving to India.
Burma fell in 1942. It was incorporated as a Japanese territory in 1942, joining the entire Southeast Asian region.
In the early phases of the war, Japan conquered the region quickly as the colonial powers Great Britain, France, and the Netherlands were unable to fight as they were completely engaged in Europe against the Axis powers.
World War II also put the entire idea of freedom for India on hold. After World War II Great Britain agreed to independence for the colony. Lord Viceroy Mountbatten was charged with overseeing the transition. His mandate included specific instructions included not to partition the colony. That clearly did not work.
The partition broke the colony up into 2 independent countries - India and Pakistan. Pakistan had an Eastern and Western Province separated by the bulk of India. The division was primarily based on religions of the local people – Hindu or Muslim. Unfortunately, the partition line was drawn in London and based on older census data This caused of the many problems that still linger today. There were a few separate principalities in India proper that were advised to join one or another of the countries.
Violence and Conflict
The immediate result of the partition lines caused heavy conflict in along the Indian - Western Pakistan border, particularly the Punjab region. The partition divided Punjab between Pakistan and India, but much the population was stuck on the wrong side of the border. Approximately 6 million people moved west to Muslim Pakistan. The movement of 5 million Hindus and Sikhs moved east to India. Conflicts and the movement of citizens left between 200,000 and 2 million people dead.
In the east, the same conflict between Hindus and Muslims occurred as the province of Bengal was divided – also displacing millions and bringing religious war. Migration across the Bengal border between India - Western Pakistan was about 1 million Muslims moving into East Pakistan and abut 2 ½ million Hindus moving to Indian Bengal.
Jammu and Kashmir
Jammu and Kashmir was a “princely state”. Like other princely states in the south, the government was encouraged to join either one of the new countries. Without going too far into the issues (which are thorny themselves) a bloody set of massacres and fighting occurred, resulting in the current situation where the border is still not defined. Jammu and Kashmir have been further wracked by violence from Indian forces. There is also a low level dispute between India and China on the northwest borders.
Bangladesh
The province of East Pakistan (now Bangladesh) was more populous than West Pakistan (now just Pakistan) but housed a different cultural population of Bengalis. East Pakistan Internal struggles broke out into war from about 1971. In that same year Pakistan killed from .3 to 3 million Bengalis. Millions more fled over the border into India. Allowing Bengalis freedom to strike from India, Pakistan attacked India in late 1971. India retaliated against Pakistan in both the east and west. Pakistan surrendered to Bangladeshi and Indian forces in December ending the 9-month war. This is another cause from Pakistani Indian belligerent stances towards each other.
Current Status
Burma / Myanmar
The government of Burma was overthrown by the military and changed the name to Myanmar. The country has been involved in a decades long civil war with occasional bouts of normalcy and partially free elections. Economic growth has been sporadic, but investments from China (and lingering investments the US and EU) have spurred growth, particularly around Yangon (formerly Rangoon) and Irrewaddy Valley. In 2020, Myanmar was the fastest growing economy in the world.
The US normally gets news of Myanmar either due to sanctions or their treatment of the Rohingya minority.
East Pakistan / Bangladesh
When the province of Eastern Pakistan won independence as Bangladesh. The country of Bangladesh is a little smaller than Iowa or Greece. The population is over 170 million people. For comparison, Iowa’s population is 4 million and the population of Greece is 10 ½ million people. So super crowded.
Bangladesh is also cursed with a geography where most of the population lives in the fertile Ganges Delta (the largest in the world). But this rich farmland is very often flooded by the Ganges causing massive destruction. It is also sits at an extremely low elevation. It is estimated that 10% of the country would be underwater if the sea level rises a meter (about 3 feet). And the sea level is rising.
On the other hand, Bangladesh has grown its economy very fast. It has the second largest GDP within southern Asia. The per capita income in Bangladesh is now higher than either India or Pakistan. If it is the US press it is normally because of a natural disaster.
India
India has prospered economically, particularly as the home of outsource technology workers. A large middle class of technology workers and others live alongside a very rich upper class and overwhelming lower class. India has made huge strides in bringing people out of extreme poverty but a very very large population hampers the efforts.
Climate Change is a very real threat to India. Summer heat waves of both high temperatures and very high humidity have caused a 55% increase in heat related deaths. The country also has 350 million people living along the coast. Climate change also reduces snow in the Himalayas which provide water for most of the population.
Pakistan
Pakistan is an example of when geography and economics drive regional conflict. Nearly 2/3 of Pakistan is arid desert. The river Indus flows through the country and is a lifeline to the desert south west. But the Indus also floods often, putting the population at risk. Flooding is magnified by the monsoon rains that occur from June to September.
Pakistan was also the focus of interest during the Afghanistan conflict and received large payments from the United States for rights to get supplies into Afghanistan. Those payments have dropped to near zero since the war.
Pakistan, in the US, is known for it’s governmental system which vacillates between strict Muslim leaders and the military.
Nuclear Weapons
As noted previously, the India – Pakistan relationship has be defined by border skirmishes, low level conflicts, and some limited military strikes. In 1974 India tested its first nuclear weapon. This prompted an acceleration of Pakistan’s efforts to build a similar weapon. Pakistan exploded their first nuclear weapon in 1998.
Pakistan and India appear to have stopped escalation since the advent of their nuclear arsenals. Since then, there have been fewer cross border attacks, but both countries have experienced internal cultural divisions. More nationalistic governments have been established by India, Pakistan, and Myanmar.