The Anu’s ship was fully self-sufficient, it did not need outside resources to function. However, with all their technology they could not find a way to stop the disastrous effects the local energies were having on their sanity.
After several cycles had passed, they learned that certain metals, like gold, helped to diffuse the incoming energies at least to some extent. They found areas with conductive metals, and began to extract them. Had they been healthy, they would not have gone even this far.
Their initial landing was under water. The Anu created several bases here, from which they could interact more easily with the surface. The location they selected was the area we know as the Mediterranean.