Route 111 (Desert)

You can visit this area as soon as you get the Go-Googles. The area has lots of hidden items, and trainers. The area has an everlasting Sandstorm which will cause a weather effect during wild Pokemon encounters or trainer battles. The level range of trainer Pokemon will range from LV20-LV28. It is recommended to explore the area as early as possible to be able to take advantage of the extra cash and experience you'll get from the trainers and also collect more items.

This is where you'll find the Desert Ruins, where you can find the Legendary Pokemon Regirock. The ruins can only be accessed after completing the puzzle in the Sealed Chamber located in Route 134.