A small stream that rose in the uplands beneath the Halifirien that flowed through the Firien Wood, then north and east across the plains of Rohan. It met the Entwash after that river had divided into many branches to form the marshy Mouths of Entwash. The Glanhír is perhaps better known by the name used by the Rohirrim: the Mering Stream. It marked part of Rohan's border with Gondor, and its name, meaning 'border stream', reflects that fact.