 Webb may have been the first to differentiate between the Hiwassee Island culture (c. 1000-1300 AD) and the Dallas culture (c. 1300-1600 AD) that once dominated the Tennessee Valley (Webb noticed that one culture used "large-log" structures while the other used "small-log" structures).Webb also speculated, based on his findings in the Norris Basin, that the Cherokee were relative newcomers in the Tennessee Valley, arriving in the area no later than the late 17th century.Although when the Cherokee actually arrived in the Tennessee Valley is still debated, the tribe was in control of the region when the first English explorers and traders crossed the Appalachian Mountains into the East Tennessee area in the mid-18th century.