Donets Basin (dənyĕtsˈ) [key], abbreviated as Donbas dənbäsˈ, industrial region (c.10,000 sq mi/25,900 sq km), E Ukraine and SW European Russia, N of the Sea of Azov and W of the Donets River. It is located mainly in Donetsk and Luhansk regions of Ukraine and extends E into Rostov region. The Donets Basin forms one of the densest industrial concentrations in the world. Based on a formerly rich supply of coal, the Donbas was extensively developed in the 19th and 20th cent. because of its proximity to markets in European areas of the Russian Empire and the Soviet Union and to large deposits of ferrous metals in Ukraine (Kryvyy Rih, Nikopol). Two types of coal predominate in the Donbas: anthracite, in the south and east (used mainly by thermal power stations), and bituminous, in the southwest and north (used mainly for coking). Major coal centers include Shakhty (Russia) and Shakhartsk, Horlivka, and Krasnyy Luch (Ukraine). Other minerals besides coal are produced in the region, and there are also heavy-machinery, chemical, and power plants. Major iron- and steel-producing centers are Donetsk, Yenakiyeve, Makiyivka, Kramatorsk, and Alchevsk. The development of the Donets Basin began c.1870, and by 1913 it was the source of virtually all the coal and more than half of the iron and steel produced in czarist Russia. Strikes in this region in the late 1980s, coupled with strikes in the Siberian Kuzbas region, brought Soviet industrial production to a standstill and caused a crisis for the Communist government.