It was the biggest migration of people ever; an unprecedented event. It happened continuously between the years 2029 and 2037. The demographic distribution of India changed suddenly; a change that brought along with it both hope and sorrow; a change that many people felt was imminent, given nature's tendency to equalize.
The seeds of this were sown back in 1991, when Manmohan Singh, then India's finance minister did the inevitable: he liberalized the economy. Foreign investement came in, lifted parts of India from a stagnant rut of inefficiency and corruption. Peninsular India, given its lower population densities (and its higher literacy rate) responded way sooner than North India to this sudden stimulus. South India developed at a whooping 11% every year; North India at a slower 6% (bringing the overall rate to 8%).
So, the Inevitable happened. The states of Tamil Nadu, Andhra Pradesh, Kerala, Maharashtra, Gujarat, Bengal, Punjab, Haryana, Himachal Pradesh and certain North-Eastern states had excellent individual macro-economic indicators. South India became a cultural and Industrial hub. The Tamil and the Telugu film Industries put together made more money than the Hindi film Industry. Population in the southern states began to saturate; poverty started going down - and soon extreme poverty became history. Life expectancy began to tough the 70s.
The Indian cricket team began to be dominated by people from the South. A private company called "southern sport" started a regional cricket league, where 20-20 matches were played between cities. Matches between Mumbai and Bangalore became a significant fixture.
Dharavi, formerly Asia's largest slum colony in Mumbai had disintegrated. High rises replaced the slums; labourers lived in centrally air conditioned homes in sea of humidity that Mumbai is. Even Chennai grew in popularity. Hyderabad had hosted the olympics, India had won sixteen gold medals in the same. Universities in South India had gained international repute; Chennai itself housed 8 Nobel Laureates.
Up North, things were miserable, save the Delhi Region, which housed lots of call centers for the people down south. Delhi was the world's largest urban agglomeration now; It had overtaken Tokyo recently in 2029. People from all over North India used to come to Delhi for Jobs. North India had a lot of mines - and the miners in Bihar lived in slums. North India's population, in stark contrast with South India was still on the upswing. Nearly 800 million of India's 1.4 billion hailed from Bihar, UP, Uttaranchal, Chattisgharh and MP. Finding a job was tougher.
Down south, migrant labourers from the North started finding jobs that paid well. They could easily support their families up north. Students from the North applied to universities in the south; and were more often than not, accepted with financial assistance. The economy of the south consistently grew faster than the North.
A massive influx (100 million or so) of Hindi speaking people to the south of the Arravalis meant a permanent change in India's demographic make-up. Laws were passed to stem this migration; but were soon negated by the supreme court. A cultural dilution of massive proportion took place.
India is now a more homogenous, if not happier place.