BEIJING - Back in the 1990s, Long Youfu had a pretty horrible job, creeping into scorching kilns and polishing ceramic tiles. Today, he merely monitors an automatic loading- and-unloading system and presses some buttons on a polishing machine.

Long works in Guangdong Wonderful Ceramics Group in South China's Dongguan, the city which supplies one-fifth of the world's smartphones and one-tenth of the world's shoes. It's often called "the factory of the world".

Average annual wage in Dongguan had nearly doubled in five years to 46,000 yuan ($7,100) in 2016.