In 1983, Zhen Zhicheng, then 6 years old, was free as a bird in the steep mountains of Hubei province, where his parents, both Beijing natives, had been living since 1970 alongside tens of thousands mobilized from around China to work at the No 2 Automobile Plant in the small town of Shiyan.
The late American anthropologist Clifford Geertz once described a result of "agricultural involution", which was caused by internal pressures due to population growth, as increasing labor intensity in the paddy fields. China's agriculture faced the same problem, and its farmers were bound to the farmland for thousands of years.
The sheer scale and radical nature of transformations in China in the past century suggest that very few could claim not to be migrants of one sort or another.