Keres is now considered a language isolate. In the past, Edward Sapir grouped it together with a Hokan–Siouan stock. Morris Swadesh suggested a connection with Wichita. Joseph Greenberg grouped Keres with Siouan, Yuchi, Caddoan, and Iroquoian in a superstock called Keresiouan. None of these proposals has been validated by subsequent linguistic research.
