The report of Cabeza de Vaca, commonly designated as his "Naufragios," is as yet the earliest printed source known with reference to the Rio Grande Pueblos, concerning whom it imparts some vague information. The briefness and vagueness of that information calls for no adverse criticism, for Cabeza de Vaca plainly states that he writes of these people from hearsay and that his information was obtained near the mouth of the Rio Pecos in western Texas. What he afterward learned in Sonora with respect to sedentary Indians in the north is hardly connected with the Rio Grande region. The same may be the case with the information obtained by Nuno de Guzman in 1530 and alluded to by Castaneda. That Nuno de Guzman had gained some information concerning the Pueblos seems certain, but everything points to the Zuni region as the one mentioned by his informant. The same is true of the reports of Fray Marcos de Nizza and Melchor Diaz, which clearly apply to the Zuni Pueblos, the most easterly settlement of sedentary Indians alluded to being the Queres pueblo of Acoma. It is to the chroniclers of the expedition of Coronado, therefore, that we must look for the earliest definite information concerning the Rio Grande valley and its inhabitants. It must be borne in mind that the expedition of Coronado was not a mere exploration. What was expected of its leader, and indeed peremptorily demanded, was a permanent settlement of the country. Coronado and his men were not to return to Mexico except in individual cases. The Viceroy Mendoza wanted to get rid of them. Whether Coronado was a party to the secret of this plan is doubtful; the indications are that he was not, whereas Fray Marcos of Nizza certainly was, and perhaps was its original promoter. The printed sources on Coronado's march may be divided into two chronologically distinct classes, the first of which comprises documents written in New Mexico in the years from 1540 to 1543; these reflect all the advantages and disadvantages of the writings of eye-witnesses. The mere fact that one had been a participant in the events which he describes is not a guaranty of absolute reliability: his sincerity and truthfulness may be above reproach, but his field of vision is necessarily limited, and the personal element controls his impressions, even against his will, hence his statements. These earliest sources regarding Coronado consist of the letters of Coronado himself (with the related letter of Viceroy Mendoza), and several briefer documents written in New Mexico but without indication of their authors. The last two letters written by Coronado alone touch upon the Rio Grande Pueblos--those of August 3, 1540, and October 20, 1541.