 The Dry line, an imaginary line that separates moist air from an eastern body of water and dry desert air from the west, usually bisects the state and is arguably an important factor in pre-historic settlement, with agrarian tribes settling in the eastern part of the state and Hunter-gatherer tribes settling in the western part of the state.People have lived in what is now Oklahoma as long as the oldest known documented Paleo-Indian cultures in the field of archaeology/anthropology.From the earliest known projectile points of the Clovis Culture to the highly advanced Folsom and breaking off into the lesser known cultures whose artifacts and kill sites have been well documented all over the state (Dalton, Midland, HellGap, Alberta/Scottsbluff, Calf Creek), humans were present and very active in what is now today known as the State of Oklahoma.