In connection with the military expansion of Mexico, mention must be made of the guild of travelling merchants, or Pochteca. The Pochteca were not peculiar to Tenochtitlan; similar guilds were found in Azcapotzalco, Uitzilopochco and Quauhtitlan, but those of Tlaltelolco were by far the most famous. Membership of the guild was a valued privilege, since the merchants stood high in the royal favour; only the sons of merchants could become merchants except by permission of the chiefs. Like the other calpulli, the Pochteca were under the direction of headmen, who represented the guild in external business, but they were privileged in so far as they were exempt from agricultural labour and from the ordinary judicial system, delinquents being judged by their own headmen. They worshipped special gods, chief of whom was the deity Yacatecutli, and joined in private ceremonies of a kind, as far as can be judged, far more elaborate than those of the other guilds. To some extent it is true that the importance of the guild grew with the expansion of Mexican power, but it would be almost equally true to say that Mexican power grew with the extension of the merchants’ sphere of operations. They acted in fact as the pioneers of Mexican political influence, they penetrated fearlessly into hostile countries either openly and armed, or disguised, and for this purpose learned the speech of foreign nations. They acted as spies of the king, and in one case a body of Pochteca of Tlaltelolco were besieged in a town in Anauac Ayotlan, or the district around Tehuantepec, and, after four years, succeeded unaided in reducing the province to submission. For this deed they received special privileges and _insignia_ from the king Auitzotl, including the right to wear lip-plugs of gold, while their captains bore military titles. At the time of the Spanish conquest these merchants made extended journeys far into Chiapas and Tabasco, and penetrated even to Guatemala. The gradual extension of their sphere of operations can be seen in the wares which they imported from time to time, and as this has a bearing upon Mexican history it is worth mention. In the reign of Quaquapitzauac, first king of Tlaltelolco, the imports were brilliant feathers from the low countries; under his successor, quetzal-feathers, turquoise, chalchiuitl and cotton textiles were added; in the next reign, lip-plugs of precious stones, gold, skins, and a greater variety of feathers were introduced; and under Moquiuix, the last king, cacao became an article of merchandise. This information is from Sahagun, who, in a later passage, states that precious stones were collected especially in southern Vera Cruz and Tabasco, and quetzal-plumes from the region around the present San Cristobal in Chiapas.