Race Metamorphosis!!

You're not entirely correct. Mages also live in the desert. There are many buildings with mages there. And it's not just golems; there are inhabitants. The highlands are located on the southwestern coast of the country, but there are also mountains in the desert. Snow in the highlands is, naturally, in the higher parts and mountain valleys. Mages also live there. And Celeste is not located on the mountains (although, judging by the picture, the city may be built on a mountain, which, like it, is in the sky), but floats under the clouds.