text: 20th century Galician oilfields made Austria-Hungary the world's third largest oil producing country after United States and the Russian Empire, with a 5 percent share of the global oil production in 1908. By 1910, significant oil fields had been discovered in the Dutch East Indies (1885, in Sumatra), Persia (1908, in Masjed Soleiman), Peru (1863, in Zorritos District), Venezuela (1914, in Maracaibo Basin), and Mexico, and were being developed at an industrial level. Austria-Hungary lost its primate on oil production which had been at the root of the 1910 Petroleum War. Significant oil fields were exploited in Alberta (Canada) from 1947. Offshore oil drilling at Oil Rocks (Neft Dashlari) in the Caspian Sea off Azerbaijan eventually resulted in a city built on pylons in 1949.
  The availability of oil and access to it, became of "cardinal importance" in military power before and after World War I, particularly for navies as they changed from coal, but also with the introduction of motor transport, tanks and airplanes. Such thinking would continue in later conflicts of the twentieth century, including World War II, during which oil facilities were a major strategic asset and were extensively bombed. In 1938, vast reserves of oil were discovered in the al-Ahsa region in the Eastern Part of the Kingdom of Saudi Arabia along the coast of the Arabian Gulf.