 The Kuma–Manych Depression (more precisely, the Manych River, the Kuma–Manych Canal and the Kuma River) remains cited less commonly as one possible natural boundary in contemporary sources.This definition peaked in prominence in the 19th century, however it has declined in usage since then, as it places traditionally European areas of Russia such as Stavropol, Krasnodar, and even areas just south of Rostov-on-Don in Asia.A lesser known definition for country grouping, is the definition used for statistical purposes by the United Nations Statistics Division (UNSD)