The earliest documentation found is on the Comecrudo: "In Escandon's account of his reconnaissance of 1747 (Escandon 1946, 61;Vedoia 1749, 155-156; Saldivar 1943, 34-35). Escandon's main source of information on Indians (Salinas' word) of the Rio Grande delta came from a Comecrudo leader, Capitan Santiago, who was clearly the acknowledged leader of other Indian groups of the area. Capitan Santiago summoned other Indians (Salinas' socialization) by use of smoke signals, and some two hundred Indian families came to the locality of Escandon's camp, which seems to have been somewhere near modern Matamoros. Escandon obtained from Capitan Santiago the native names of thirty Indian groups said to be living along the lower Rio Grande, sixteen groups south of the river and fourteen north of it. The Comecrudos were apparently more numerous than other Indian (socialized words) groups of the delta area (Rio Grande Delta) and seemed to have lived very near the Gulf coast of the river.
Although the Comecrudos of the Rio Grande also held that Spanish label, the Comecrudos of the Rio San Fernando near San Luis Potosi. The Comecrudos label or name was used rather frequently by the Spanish explorers, to identify the people of the area. The Comecrudos of the Rio San Fernando did not share the same language as the Comecrudos of the Rio Grande, but did have similar dialect and culture. The possibility also points to the Comecrudo as being nomadic.
Comecrudo in Spanish means, "Those who eat raw". The label came from the Spanish explorers' observations of the Comecrudo food being half raw from cooking in animal paunches. "Carrizos (Spanish for "canes" or "reeds") is a descriptive name that was applied after 1700 to various widely distributed Indian groups of northeastern Mexico and Texas, apparently because they lived in houses whose frames were covered by canes or reeds. As some of the groups called Carrizos were unrelated, it's not realistic to speak of Carrizos as a specific ethnic unit. Here treatment is restricted to groups called Carrizos who lived along both sides of the Rio Grande between Laredo area and the Gulf Coast. One set of the Carrizos will be referred to as Western Carrizos, the other as Eastern Carrizos. It is not possible to draw a boundary line between the two sets, but for practical purposes the division is made about midway between Revilla and Camargo.”