Bayon Obo is the world's largest known REE (Rare Earth Elements) deposit. It is located in Inner Mongolia. ‍

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Rare Earth Elements are what made smart devices and our space exploration possible; however, REE mining takes a heavy toll on the environment, draining the fertile grassland and exposing local residents to constant radiation and toxic gases. In our imagination of those 200 years, after aboveground REE was drained at the mining site in 2030, the corporate starts to force miners to build an underground mining colony that will enable them to dig for REE further down the ground. The aboveground mining district was soon deserted, and the majority of miners start to live underground in those colonies for easier access to the mine. Then, a giant reserve of REE was discovered in a new underground mine that they were digging. Driven by the tech lust of the world above, miners started to dig even deeper. The miners live under severe conditions, with constant exposure to radiation and inhalation of toxic gas. Eventually, the D-Day came when an earthquake destroyed these miner colonies in minutes. There were around 1.8 million miners who got buried in this disaster.

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