The Mouths were the refuge of the remnants of Eldar and Edain of Beleriand after the Nírnaeth Arnoediad and the Sack of Menegroth. The first rulers of this region were Tuor of the Edain and Idril of Gondolin. Their son Eärendil Half-elven, married the Half-elven Elwing, Dior's daughter. Eärendil and Elwing's sons, Elros and Elrond, were born in Arvernien.