Of this small and obscure Indian community mention is made much earlier than of all the other tribes hitherto spoken of in this volume, for Cabeça de Vaca, in his Naufragios, mentions them among the inland tribes as Atayos. In the list of eight Caddo villages, given by a Taensa guide to L. d Iberville on his expedition up the Red River (March 1699), they figure as the Natao (Margry IV, 178).
The Adái, Ada-i, Háta-i, Adayes (incorrectly called Adaize) seem to have persisted at their ancient home, where they formed a tribe belonging to the Caddo confederacy. Charlevoix (Hist, de la Nouvelle France, ed. Shea VI, p. 24) relates that a Spanish mission was founded among the Adaes in 1715. A Spanish fort existed there, seven leagues west of Natchitoches, as late as the commencement of the nineteenth century. Baudry de Lozières puts their population at one hundred men (1802), and Morse (1822) at thirty, who then passed their days in idleness on the Bayou Pierre of Red River. Even at the present time they are remembered as a former division of the Caddo confederacy, and called Háta-i by the Caddo, who are settled in the southeastern part of the Indian Territory.
A list of about 300 Adai words was gathered in 1802 by Martin Duralde, which proves it to be a vocalic language independent of any other, though a few affinities are traceable with the Pani dialects. The orthography of that vocabulary cannot, however, be fully relied on. The original is in the library of the American Philosophical Society, in Philadelphia. Rob. G. Latham, in his “Opuscula; Essays, chiefly philological,” etc., London 1860; pp. 402-404, has compared Adahi words with the corresponding terms of other North American languages, but without arriving at a definite result.