Soviet leaders developed Central Asia as a major supplier of metals, minerals and agricultural produce, particularly cotton.
The collapse of the USSR plunged the area into decline as subsidies dried up and Soviet markets disappeared.
Recovery has depended on countries' natural resources and commitment to reform.
Kazakhstan has fared best. Reforms have paved the way for foreign investors to develop its copious energy resources, but over-reliance on oil and gas is a concern.
In contrast, Turkmenistan has significant gas reserves but has implemented little change and struggled to exploit and sell the commodity.
Uzbekistan also has oil and gas, and although slow to attract investment, is increasing production.
Tajikstan and Kyrgystan lack energy resources and rely on exports such as cotton, gold, aluminium and, in Kyrgystan's case, hydroelectricity.