Plateau of Leng

The Plateau of Leng is a region of Daxia closed off to normal human habitation or travel since at least the 1920's. It is reputed to be the region dominated in far antiquity by the semi-mythical Kingdom of Leng. Internet conspiracy theories posit that it isn't an actual place but a metaphysical realm where the laws of causality do not apply.

Theories

 * The government is battling a long running armed insurgency in Leng.
 * It was used as a testing ground for weapons of mass destruction and experimental devices that have rendered it a dead zone.
 * There are entire underground cities full of slaves and dissidents, everyone has mutations to live below ground permanently.
 * The government has a giant drill and is using it to dig down into the planet's mantle.
 * The Kingdom of Leng was inhabited by extraterrestrial lifeforms and their ruined cities are being explored by the government
 * The government has built an interdimensional portal and is bringing Daxian people from other dimensions to help conquer the planet.
 * The government is trying to keep Khov'Anilessa the Destroyer of Dreams from breaking out of an underground glacier.
 * It is inhabited by giant worms with mind controlling powers.