The byzantine origin of the word vlach is supported by the historian Stelian Brezeanu who considers that one of the first accounts about Romanians south of the Danube, referred to by the name "vlachorynchini" (the vlachs near the Rynchos river), is present in a historical account about the Kastamonitou Monastery which was written in the 17th century but based on a 9th century byzantine source.