In between the Star Hills there is a large clearing where the clans gather under the full moon for the Gathering. If you continue up the hills, between the ledges on the hills where the Clan Leaders sit, you'll come across Star Cave after a long walk up the hills. In this cave the moonlight shines down, sleeping in the moonlight allows you to contact StarClan. This is where Clan Leaders and Medicine Cats go to talk to StarClan.