Trat, Trath, Treroit, Treuroit, Tribruit
An unidentified river in Britain that, in Nennius, was the site of Arthurís tenth battle against the Saxons. As in all of Arthurís twelve battles, Arthur was victorious.
Nennius may have intended the river Ribroit in Somersetshire or the river Ribble in Lancashire. A Welsh poem alludes to a fight at a river called Tryfrwyd, which may be identical.