Timber felled in the forests of North Russia floats 2,000 miles down the Volga and its tributaries to the Caspian Sea and the oil-fields of Baku. This avenue of communication has been important throughout Russian history. Along the Volga are scattered colonies of many alien peoples, the Votiaks, the Mordva, the Mari, the Chuvash, the Kazan Tatars, the Bashkirs, the Volga Germans, the Kalmucks. The Caucasian isthmus is even more of an ethnological museum. Besides the Georgians, Armenians, and Azerbaidjan Tatars, which are the principal peoples of Trans-Caucasia, there are mountain tribes of obscure origin, while North of the main range a variety of peoples, roughly classified as Circassians, inhabit the western districts, and another group of peoples, equally roughly classified as Lesghians, occupy the wild country along the Caspian coast. A journey along this route gives some idea of the heterogeneous population under Soviet rule, besides affording glimpses of important sections of the Five Year Plan.