Throughout history, the territory of Oklahoma has proven to be one with the greatest resources within the United States. All of these "treasures" apply for Oklahoma. 1. Gold and Silver: Since de Soto's and Coronado's Spanish expeditions, gold and silver were primary reasons to explore Oklahoma. Around 1765 there was permanent mining activity in the Wichita Mountains. 2. Fur: French fur traders moved into Oklahoma along the Arkansas and Red rivers, founding villages of Fernandina, San Bernardo, and San Teodoro. 3. Salt: Oklahoma's first commercial salt company (Campbell's Salt Works) came in 1815 for taking advantage of salt deposits on the Grand River. 4. Oil: The Cities of Glenpool and Tulsa became important because the discovery of oil fields in 1905, which caused an economic boom that drove the growth of "Oil Capital of the World", Tulsa.