In the 1980s, the Western Siberia region, also known as the Russian Core, made the Soviet Union a major world Oil producer, allowing for peak production of 12.5 million barrels per day in 1988. Following the collapse of the Soviet Union in 1991, Russias oil production fell precipitously, reaching a low of roughly 6 million bbl/d, or around one-half of the Soviet-era peak. Several other factors are thought to have caused the decline, including the depletion of the countrys largest fields due to state-mandated production surges and the collapse of the Soviet central planning system. A turnaround in Russian oil output began in 1999. Many analysts have attributed the rebound in production to the privatization of the industry following the collapse of the Soviet Union. The privatization clarified incentives and increased less expensive production. Higher world oil prices (oil prices tripled between January 1999 and September 2000), the usage of technology that was standard practice in the West, and the rejuvenation of old oil fields also helped raise production levels. Others partially attribute the increase to after-effects of the 1998 financial crisis, the subsequent devaluation of the ruble, and the fall in oil prices.