All Caddoan languages are critically endangered, as the number of speakers has declined markedly due to colonial legacy, lack of support, and other factors.

The Caddo, for example, lived in northeastern Texas, southwestern Arkansas, and northwestern Louisiana, as well as southeastern Oklahoma.

In the case of Proto-Caddoan, it appeared to have divided into two branches, Northern and Southern, more than 3000 years ago (The division of the language implies also a geographic and/or political separation).

South Caddoan, or Caddo proper, evolved in north-eastern Texas and adjacent Oklahoma, Arkansas, and Louisiana.

[3] Adjacent to the Caddo lived the Eyeish or Ais—not to be confused with the Ais of Florida—who also spoke a language that may have been related to Caddoan.