Its source is in the mountains on the western part of North Macedonia, northwest of Demir Hisar.

It leaves the Pelagonia valley at the Staravina village and goes in the biggest canyon in North Macedonia, the Skočivir valley and flows into the Vardar River between Rosoman and Gradsko.

The name Crna Reka means "Black River" in Macedonian, a translation of its earlier Thracian name, Erigon (Ancient Greek: Ἐριγών, romanized: Erigón), meaning "black", akin to Greek érebos, "darkness"; Armenian erek, "evening"; Old Norse røkkr, "darkness"; Gothic riqis, "darkness"; Sanskrit rájas, "night"; and Tocharian B orkamo, "dark".

[1] The Erigon River is mentioned by Arrian in the Anabasis of Alexander,[2] Livy in the History of Rome[3] Strabo in the Geographica,[4] Athenaeus in the Deipnosophistae.

[5] The Roman provincial capital of Stobi sat at the intersection of the Vardar and the Crna[6]