There was a Sky Mountain in Forsaken Heaven City and it was the largest mountain range there; it meandered like a huge dragon. The Divine Palace wasn't the only one built on the Sky Mountain. All major influences were basically based there after all, just at different parts of the mountain.
The Sky Mountain was considered to be a Spiritual Spring. A sect could be built where a Spiritual Spring could be found.
The mountain was very big and the peak was extremely vast, just like a plateau. This showed how vast the Sky Mountain was.