Book excerpt: The largest migration in history is taking place in China today, off the radar of the world's major media. Since the 1990s at least 120 million Chinese peasants have left the countryside for the big cities to work in factories, on construction sites, in catering and prostitution - typically without the most basic rights or protections. Here van Luyn relates the remarkable tales of migrant workers who have helped fuel the explosive growth of the People's Republic of China.