 In 1873, exploration and development of oil began in some of the largest fields known to exist in the world at that time on the Absheron Peninsula near the villages of Balakhanli, Sabunchi, Ramana, and Bibi Heybat.Total recoverable reserves were more than 500 million tons.By 1900, Baku had more than 3,000 oil wells, 2,000 of which were producing at industrial levels.