The Mexicans have left abundant traces of their language in Costa Rica, especially throughout its northern half. Many of their words are now in common use and incorporated into the Spanish spoken there. Notably such words occur in the names of plants, animals and geographical localities. In 1569 the Adelantado Peráfan de Rivera made an elaborate detailed enumeration of the Indians and found their total number to be 25,000. Mr. M. de Peralta says the Nahuas (Aztecs) and Mangues (Chorotegas), Güetares, Viceitas, Térrabas, Changuenes, Guaymies, Quepos, Cotos and Borucas were the principal people who occupied the territory of Costa Rica at the time of the conquest. The Nahuas came from the north, and if the Mangues did not go from Chiapas, it is necessary to infer that from the Gulf of Nicoya and the shores of the lakes of Nicaragua and Managua they extended to the south of Mexico, where, up to a few years ago, their language was spoken at Acalá. The Mangues, or Chorotegas, at the time of the Mexican invasion, occupied the peninsula of Nicoya and all the lands surrounding the gulf of that name. They were then, no doubt, the most powerful and advanced people in Costa Rica, and carried some of their arts, such as pottery, sculpture, weaving, and tilling the ground, to greater perfection than any people occupying the region between their territory and that of the Chibcas on the table-land of Colombia. In their graves are found gold ornaments and specimens of the ceramic art showing taste in design superior to any that the present civilized Costa Rican Indian can manufacture. These graves also contain beautiful specimens of obsidian, greenstone and even finely wrought jade tools and jade ornaments, knives, axes, arrowheads, amulets, rings and a multitude of stone idols, seats, etc. The Mangues appear to have manufactured gold extensively into jewelry. The Güetares made their homes on the slopes of the Turialba. Irazú and Barba to the southeast of the Mexicans and Chorotegas, and, in a less degree, they shared in the skill and advancement of the latter, but their pottery was inferior in artistic method and quality of material and workmanship, judging from collections in the National Museum of Costa Rica. Peralta says, “The Nahuas and Mangues of the regions of Nicoya have completely disappeared, although the first still survive in Mexico, and the latter are represented here and there by a descendant in Masava (Nicaragua) and in Acalá (Chiapas).” The Nahuas (Aztecs) left notable monuments of their material civilization and of their scientific attainments, and a language that served as the instrument of a cultivated and thoughtful race.