Dorthonion

Dorthonion is a highland country of the First Age in The Silmarillion, lying along the northern march of Beleriand with the wide grass plain of Ard-galen and Morgoth's mountains beyond it. It runs some sixty leagues from east to west. On its northern side the ground climbs gently out of the plain and is covered in great pine forests, and a mountain called Orod-na-Thôn stands at its centre. The sheer Ered Gorgoroth close it in on the south, turning north at the eastern end to form the Pass of Aglon between Dorthonion and the hill of Himring; the upper Sirion runs down its western flank. Angrod and Aegnor, sons of Finarfin, hold the land, and its north-eastern slopes, called Ladros, are given in fief to Boromir of the House of Bëor.