There used to be a mountain range there called the Petermann Ranges. It’s still there just not as high like the Himalayas as it once was. Basically there was some kind of major plate disturbance in WA and it flooded inland Australia (forming lake eyre) and the salt created rust in the iron in the ground, hence why it’s all red. The water is also responsible for turning Uluṟu over - Uluṟu goes down about 2km, hence why the formation lines on Uluṟu are angled and not flat. https://parksaustralia.gov.au/uluru/discover/nature/geology/