https://www.macrotrends.net/1369/cru...-history-chart

This is a good chart to get an idea of the global oil price around that time. Look at how much Russia was able to sell its main export for in the nineties, look where it was in 97, then look what happened to the price in the noughties (Putin came to power in 2000).

He's not an economic genius, he was ust very lucky.