A 1970 km long river forming the border between the Scythae and the Sarmatae (Hdt. 4,21; according to Plin. HN 6,20 called Silis by the Scythae) and flowing into the Maeotis, modern Don. Sarmatian tribes lived around its lower reaches from the 4th cent. BC onwards; some 15 ancient settlements are known from archaeology there.