The Echoriath were disconnected from the Ered Gorgoroth of Dorthonion by the Pass of Aglon, and formed a natural circle of rock, enclosing the valley later called Tumladen, where lay the city of Gondolin.

The Echoriath could only be crossed by way of the empty riverbed of the Dry River, which was guarded by the Gondolindrim as the Hidden Way, until they blocked it off much later. Idril daughter of Turgon later had an escape tunnel made.