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The Cirith Ninniach was a thin, rocky pass through the Ered Lómin ("Echoing Mountains") in the far northwest of Beleriand.
The Cirith Ninniach connected the land of Hithlum with the Firth of Drengist which led to the Great Sea. The Noldor used the pass to re-enter Beleriand during the Flight of the Noldor. In the following decades King Turgon built the Gate of the Noldor at the end of the pass to allow easier travel.