The very first elves were incredibly intelligent. Their sharpness of mind has only increased over the millenia. They built homes out of the natural resources Omaekah was covered with. Their tribes flourished.Edit
Of course, all good things must come to an end. No one knows what happened for sure. But the most likely theory is that dragons came down from the skies and set fire to the villages and burnt the crops. Omaekah was destroyed.