The Spanish described Plains dogs as very white, with black spots, and "not much larger than water spaniels." Plains dogs were slightly smaller than those used for hauling loads by modern Inuit and northern First Nations people in Canada. Recent experiments show these dogs may have pulled loads up to 50 lb (20 kg) on long trips, at rates as high as two or three miles per hour (3 to 5 km/h). The Plains migration theory associates the Apache peoples with the Dismal River culture, an archaeological culture known primarily from ceramics and house remains, dated 1675–1725, which has been excavated in Nebraska, eastern Colorado, and western Kansas.