The first oil lease was purchased in 1896 by a banker from Kansas named Henry Foster. The terms were generous: Foster received a “blanket lease” giving him the right to drill anywhere in Osage territory. In exchange, the Osage got 10 percent of all oil revenue, plus a $50 annual fee per well.

When Foster died suddenly, his brother Edwin took over the lease, forming the Phoenix Oil Company in 1896. The company’s first two exploratory wells were a bust, but the third well, completed on October 28, 1897, tapped a reservoir of high-grade oil 1,600 feet below the surface.

The first oil-producing well yielded 20 barrels a day, but Phoenix Oil didn't sell its first barrel until 1900, when a railroad reached nearby Bartlesville, Oklahoma. The company became the Indian Territory Illuminating Oil Company in 1901 and steadily expanded production, operating 300 wells by 1905.

In 1906, the Osage Allotment Act divided the reservation into 2,229 parcels of land.…