Grey Desert
The Grey Desert is a massive arid landscape to the east of the Hunter's Crown covering much of the western landmass. For the most part these deserts are dry, besides the central Algora River which has created a green river valley flowing through the center of the desert. In the Western region near the mountains, is the dune fields and this is where the desert has an off grey color to it predominant in the dunes of this region. As the desert expands westward the sand takes on more felsic materials giving it a lighter earthy beige as it approaches the coast.
This desert is where the Onyxscaled grew and evolved and established their great civilization thanks to their natural adaptation to the dry heat and excessive sunlight of the desert. But because the desert gets cold at night, when the Onyx invented fire, their people would gather close to it, allowing for an extended period each day for more work and for stories to be told, it is widly believed that this is where the Onyx developed their love for knowledge, around these pyres late at night telling stories to each other.

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Author's Notes
The Amazon became a desert thanks to the newly formed plateau from the NA and SA collisions (Moist air comes to the Amazon from the NE)