the Mixtec-Zapotec group of tongues; the Mixtec extending from Acatlan to Tototepec, and the Zapotec to the east, from the Nahua-speaking Teotitlan to Tehuantepec, the Mazatec occupying the northern portion of this strip. The Mixtec-Zapotec language bears many structural analogies to the Otomi group mentioned above. Along the east coast, from the Panuco valley southward, were two peoples, speaking dialects of yet another language, the Maya tongue. In the north were the Huaxtec, primitive Maya, extending as far south as Tuxpan, where they were in touch with the linguistically related Totonac. To the north they stretched beyond the Panuco, but the remains of this region are practically unknown. There is evidence too that they once extended far further west than they did at the conquest, but the expansion of the Nahua had penned them up in the narrow strip of coast, and an Aztec fortress was established as far east as Meztitlan to keep the border. The Totonac, inhabiting Vera Cruz to the south, had suffered similarly from Mexican encroachment, and the river Nautla formed a strip of Aztec territory which almost severed their country in two. At the time of the conquest their principal centres were Papantla and Zacapoaxtla. East of them, in Coatzacoalcos and Tabasco, were the peoples known to the Mexicans as Olmec, Xicalanca and Nonoualca, who, according to legend, were once settled in the neighbourhood of Tlaxcala, but were driven thence by the historical Tlaxcalans when they immigrated into the country.