|This diagram shows the relationships among the various Caddoan languages and indicates the order in which the various language groups are thought to have split from one another. How long ago the various splits occurred is not well known. Linguistic estimates suggest that, prior to about 3,500 years ago, the ancestors of all of the groups were a single people who spoke an ancestral language that linguists call Proto-Caddoan. About 3,500 years ago (1500 B.C.) the ancestors of the Northern Caddoan groups split from the Caddo and the two languages began to diversify. (Some archeologists think the initial split may have occurred thousands of years earlier.) Sometime after the time of Christ, the Proto-Northern-Caddoan speakers began splitting off, first the Wichita (about A.D. 500), then the Kitsai, and finally the Pawnee. Still later (not long before Europeans arrived) the Arikara split from the Pawnee, and the Pawnee split into two groups.