Mouths of Sirion was the delta of the river Sirion where it flowed into the Bay of Balar. It was located in West Beleriand in the land of Arvernien.
The Havens of Sirion were located in this delta, as well as a marshland and a land of reeds called Arlisgion.
History
This area may have been inhabited at an earlier time by the Teleri but when they departed for the Havens of the Falas the area was uninhabited, until Círdan established a refuge there. People, both Elves and Men began arriving into the region as a final refuge after the Nírnaeth Arnoediad.
Translations
References
Description
The location of the Mouths of Sirion in Beleriand