The Adai were a tribe of the Caddo Confederacy, they spoke a dialect closely related to that of the Kadohadacho, Hainai, and Anadarko. The tribe-was first encountered in 1529 by Cabeza de Vaca, who called them Atayo, and said they were living inland from the Gulf of Mexico. When Pierre Le Moyne Sieur de Iberville ascended the Red River of Louisiana in 1699 he heard of the people and called them Natao, stating that their village was on the river near that of the Yatasi. According to Bernard de la Harpe in 1719, the tribe was very useful to the French traders and explorers, particularly when making portages. At that time the villages of the Adai extended from Red River southward beyond the Sabine River, in Texas. The trail which connected the Adai villages became the noted “contraband trail” over which traders and travelers journeyed between the French and Spanish provinces, and one of the villages was a station on the road between the French fort at Natchitoches, Louisana and the Spanish fort at San Antonio, Texas.
With their villages scattered over territory controlled by both the French and the Spanish, the Adai were subjected to all of the adverse influences of the white race and suffered from their wars, new diseases, and alcohol to which they had been introduced, so that by 1778 they were reported by French explorer, Athanase De Mézières Y Clugny as almost exterminated. In about 1792, 14 families of the tribe, together with a number if Mexicans, emigrated to a region south of San Antonio, Texas, but they soon melted away and were lost among other Indians. Those who remained numbered about 100. In 1805 George Champlain Sibley reported a small settlement of Adai on Lac Macdon, near an affluent of Red River; which contained only 20 men, but a larger number of women. This Adai remnant had never left their ancient locality. In 1715 Domingo Ramon, with a company of Franciscans, traversed the Adai territory and started settlements. In 1716 the mission of San Miguel de Linares was founded among them in East Texas, and there were Adai also in the mission of San de los Tejas, established in 1690. About 1735 a military post called Nuestra Señora del Pilar was added, and five years later this garrison became the Presidio de los Adayes. Later, the Adai tribe was placed under the division having its official headquarters at Nacogdoches, Texas. In all essentials of living and ceremony, they resembled the other Caddo, by whom the remnant was finally absorbed.