Then you have to go through the desert to the outpost. It helps though, if while on the way you find the oasis in the desert and pick some limes and lemons from the bushes or trees. At the outpost you will find a mouse named Moufessa or something. You have to be kind and give him what he would like. It's either the lemons or limes. He gives clues. After that he might give you a pulse stone to use to find the hidden ruins in the deser by placing the stone in a boulder. The ruins then come out from underneath the sky. Hope this helps.