Question

why has the largest migration history taken place in china?

Answer 1

Not sure if Writing is the place for a question like this, you might get a better response in History but I'll help out!

Migration patterns in China were massive due to one word -- work.

As China's economy began to explode, so did the need to find cheap labor to man the growing number of manufacturing jobs that began popping in the larger cities most of which were along the coast. Factories in coastal cities and elsewhere lured millions of workers from inland provinces out into other regions resulting in a human tidal wave of job seekers.

On holiday, many workers would then sweep onto trains, bikes, cars, and whatever else to return home and share what they earned with their families. It's as if half the population of your town made it a point to move out to the next state for work for a few months before returning home.