The ancient Greek considered Evros as the largest river in the world. Alcaeus referred to it as the "best river", Euripides called it "silver-yielding" and Plinius "gold-flowing". According to Plutarch, the original name of the river was Romvos, later replaced with the name of Evros, son of Cassander, a mythological king of Thrace.
Cassander was separated from his wife Crotonike and married to Damasippe who had passionately fallen in love with Evros, the son of Cassander from his previous marriage. Evros did not correspond to her love so she decided to take revenge by saying to Cassander that Evros attempted to rape her. Impelled by his wife detractions, Cassander went after his son Evros who run away to escape from his father, fell in Romvos river and was drawn. Since then, the river was named after the tragic young man.
The Evros river is connected with many legends of the area. The seer and singer Orpheus lived here and instituted the orphic mysteries. The cult of Bacchus and Dionysus also flourished in the area as well as the cult of the Kabeiroi in Samothrace. The head and the lyre of Orpheus ended in the waters of Evros river after he was tragically killed by the Maenads. Orestes, prompt by an oracle, arrived at the Thracian city of Ouskoudama after the murder of his mother, Clytemnestra, took a bath in the river to get rid of the Erinyes and founded a new city naming it Orestias.