 Romantic legend attributed the forts to Welsh Indians, who supposedly arrived centuries before Christopher Columbus reached the Caribbean; however, archaeologists and other scholars have found no evidence for that theory and believe that the cultural development was engendered by the Mississippian culture.Evidence suggests that after the collapse of the Hopewell, Indiana had a low population until the rise of the Fort Ancient and Mississippian culture around 900 AD.The Ohio River Valley was densely populated by the Mississippians from about 1100 to 1450 AD.