The Encircling Mountains were originally part of the Ered Wethrin, but had been separated from the main massif by the vale of the upper Sirion. They were separated from the Ered Gorgoroth by the Pass of Anach.

In the middle of the Echoriath was the hidden valley of Tumladen, with the hill of Amon Gwareth in its centre. Gondolin was built by Turgon upon the slopes of Amon Gwareth.