Teiglin.

River Teiglin had its wells in Ered Wethrin South of Dor-Lomin and had three tributaries but itself he became a tributary to Sirion. The first 30 miles South-East ran Teiglin alone from the mountains and hills ahead the great plain Taleth-Dirnen at its Western shores until the water from Glithui joined from the Eastside and Teiglin changed to a more southern course 20 Miles before the junktion with Malduin also comming from the Eastside. Another 20 miles into the eaves of Forest of Brethil and to the Crossing of Teiglin from where it ran 15 miles until Celebros, the last tributary comming from the Forest of Brethil joined. From this point Teiglin took a far more Eastern, almost directly East, course following the fringes of Brethil at its now Northern shore 60 miles until it met Sirion and became a tributary to him. After the junktion with Celebros had Teiglin delved a deep and narrow gorge the Cabed-en-Aras where he ran swift and rapidly.