The first oil source in Indian territory was drilled in 1885 in Atoka County , Choctaw Nation , Oklahoma , though it was not completed until 1888 . The First Oil Well in Indian Territory was drilled in 1885 in Atoka County , Choctaw Nation , Oklahoma , though it was not completed until 1888 . The first oil source in Oklahoma was drilled in 1885 in Atoka County , Choctaw Nation , Indian territory , although it was not completed until 1888 .