They worked as factory hands, in the coal business and as farmers. Their spirits rose when a coal boom promised to bring factories and jobs to this land of grassy plains in Inner Mongolia. When the boom ebbed, they looked for work wherever they could.
Today, many have found it at a place that makes money — the digital kind.
Here, in what is locally called the Dalad Economic Development Zone, lies one of the biggest Bitcoin farms in the world. These eight factory buildings with blue-tin roofs account for nearly one-twentieth of the world's daily production of the cryptocurrency.
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Based on today's prices, it issues $318,000 in digital currency a day.
From the outside, the factory — owned by a company called Bitmain China — does not look much different from the other buildings in the industrial park.
Its neighbors include chemical plants and aluminum smelters. Some of the buildings in the zone were never finished. Except for the occasional coal-carrying truck, the roads are largely silent.
Inside, instead of heavy industrial machinery, workers tend rows and rows of computers — nearly 25,000 computers in all — crunching the mathematical problems that create Bitcoin.
Workers carry laptop computers as they walk the aisles looking for breakdowns and checking cable connections. They fill water tanks that keep the computers from melting down or bursting into flame. Around them, hundreds of thousands of cooling fans fill the building with whooshing white noise.
Bitcoin's believers say it will be the currency of the future. Purely electronic, it can be sent across borders anonymously without oversight by a central authority. That makes it appealing to a diverse and sometimes mismatched group that includes tech enthusiasts, civil libertarians, hackers and criminals.
Bitcoin is also, by and large, made in China. The country makes more than two-thirds of all Bitcoin issued daily. Bitmain, founded by Jihan Wu, a former investment analyst, makes money mostly by selling equipment to make Bitcoins, as well as mining the currency itself.
China has mixed feelings about Bitcoin.
On one hand, the government worries that Bitcoin will allow Chinese people to bypass its strict limits on how much money they can send abroad, and could also be used to commit crimes. Chinese officials are moving to close Bitcoin exchanges, where the currency is bought and sold, though they have not set a time frame. While that would not affect Bitcoin manufacturing directly, it would make buying and selling Bitcoin more expensive in one of its major markets, potentially hurting prices.