Esgalduin was the main river of Doriath. The Esgalduin flowed from the hills of Dorthonion through Doriath past the caves of Menegroth under the Stone Bridge leading to the gates of the city, and finally meeting up with the River Sirion in the west. The Esgalduin had two unnamed upper branches of its own in Ered Gorgoroth. One ran along the border between Dor Dínen and Nan Dungortheb, and the other ran west for about 20 miles from the mountains into Nan Dungortheb and further south-east until merging with the first.