sentences:  Tributaries of the Shannon drainage basin located in the county include the rivers Mulcair, Loobagh, Maigue, Camogue, Morning Star, Deel, and the Feale.It is thought that humans had established themselves in the Lough Gur area of the county as early as 3000 BC, while megalithic remains found at Duntryleague date back further to 3500 BC.The arrival of the Celts around 400 BC brought about the division of the county into petty kingdoms or "túatha".