pochtecatl.

huel mellahuac yn inantzin catca Sta maria cuepopan chane catca çan pochteca ymichpoch = It is certain that this one's mother was a resident of Santa Mariá Cuepopan [and was] only a merchant's daughter. (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 2, 102–103.

in puchtecatl, ca tlanamacani, tiamiquini, tianquiçoani, tianquiço, tlatianquiçoani. = The merchant [is] a vendor, a seller, a practiser of commerce, a watcher of the market place. He watches the market place; [he is] a watcher of merchandise in the market place. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 59.

In qualli puchtecatl, tlaotlatoctiani, tlanênemitiani, çan tlaipantiliani, tlanamictiani, tlatmacazqui teimacazqui. = The good merchant [is] a follower of the routes, a traveler [with merchandise; he is] one who sets correct prices, who gives equal value. He shows respect for things; he venerates people. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 10 -- The People, No. 14, Part 11, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 43.

aca oztomecatl nican vallaz quinamacaquihv cacavatl tilmatli cueitl vipilli tlacallaquilli oc cequi yntla aca pochtecatl nican quicovaz niman quimilhuiz yn deputado = any trader who comes here to sell cacao, cloaks, skirts, women's shirts, or other goods he brings, if any merchant here buys it, then he is to tell the deputy (Tlaxcala, 1547)
Beyond the Codices, eds. Arthur J.O. Anderson, Frances Berdan, and James Lockhart (Los Angeles: UCLA Latin American Center, 1976), Doc. 22, 122–123.

Originally, the reference was to an inhabitant of Pochtlan, but then it came to mean trader, traveling vendor. The name probably goes back to groups then famous for trading activities. Like other ethincally derived trade designations, the ethnic connotation disappeared.
James Lockhart, The Nahuas after the Conquest: A Social and Cultural History of the Indians of Central Mexico, Sixteenth through Eighteenth Centuries (Stanford: Stanford University Press, 1992), 192.

auh intla pochtecatl mitoaya tlaatoctiz yehica ca iuhqui in tonalli in ipan otlacat amo quallj = And if he was a merchant, it was said that he would cast his things into the water. It was because such was the nature of the day sign in which he was born; it was adverse.
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 163.

ca itechpa mjtoaia, tepan qujtlaça yn xiuhcoatl, in mamalhoaztli, q. n. iaoiutl, teuatl, tlachinolli. Auh yn jquac ilhujqujxtiloia, malmjcoaia, tlaaltilmjcoaia: tealtiaia, yn pochteca. = For it was said of him that he brought hunger and plague—that is, war. And when a feast was celebrated [for him], captives were slain; ceremonially bathed slaves were offered up. The merchants bathed them. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 1 -- The Gods; No. 14, Part 2, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1950), 1.

puchteca, hiiaque in naoaloztomeca, in teiaoaloani in iaupan = the outpost merchants, the disguised merchants, the spying merchants in warlike places (16th century, Mexico City)
Fray Bernardino de Sahagún, Florentine Codex, Book 9—The Merchants, trans. Charles E. Dubble and Arthur J.O. Anderson (Santa Fe, New Mexico; The School of American Research and the University of Utah, 1959), 5.

Auh in isquich omoteneuh in tlauiztli in quetzalpatzactli: muchi conmaaquique in puchteca, in ipan oquinpeuhque, uel quinpopoloque = And all the devices, the quetzal feather crest devices mentioned, all these the merchants assumed; in them they conquered, they completely vanquished [the foe]. (sixteenth century, Mexico City)
Fray Bernardino de Sahagún, Florentine Codex, Book 9—The Merchants, trans. Charles E. Dubble and Arthur J.O. Anderson (Santa Fe, New Mexico; The School of American Research and the University of Utah, 1959), 6.
pochteca = merchants (plural)

In iquac pochteca cana yazque vecauhtica itencopa yez iz centecpanpixque amo quimivaz ixquichica y vel quimatiz yn aҫo onca ynic quincauhteuh ychan tlaca yn aҫo onca yn intech monequiz yn icivauh yn ipilvan = Cuando algún comerciante vaya a alguna parte por largo tiempo, será con autorización del centecpanpixqui, quien no lo enviará hasta no saber bien si acaso deja sustento a los que quedan en su casa, si acaso hay lo necesario para su mujer y sus hijos (Cuauhtinchan, Puebla, s. XVI)
Luis Reyes García, "Ordenanzas para el gobierno de Cuauhtinchan, año de 1559," Estudios de Cultura Náhuatl 10 (1972), 298–299.

Viernes a 4 de octubre de 1566 a[ñ]os yn ipa[n] ylhuitzin q'[ui]z in Sant Fran[cis]co yyehua[n]tin puchteca yquac quinextique yn ixiptlatzin Sant Fran[cis]co abiton in co[n]maquitia auh no yquac nez in S[an] Joseph yxiptlatzin quauhxinque q'[ui]nextique auh no ycuac nez in Jesus piltzintli ycal teocuitlatl yuhq'[ui]n matlatl yc tlatlalili auh tepozteocuitlatl yn ipepeyocyo yquac [Tachado: yquac] nez yn amanalca intlamamal tlachicomitl = Viernes a 4 de octubre de 1566 años en la fiesta que se celebró de San Francisco entonces los pochteca mostraron la imagen de San Francisco que llevaba puesto el hábito. Y también entonces apareció la imagen de San José, los carpinteros la mostraron. Y también entonces apareció el Niño Jesús, su casa era de metal precioso dispuesta como una red y de metal precioso su resplandor; entonces apareció la carga tlachicomitl de los amanalca. (ca. 1582, México)
Luis Reyes García, ¿Como te confundes? ¿Acaso no somos conquistados? Anales de Juan Bautista (Mexico: Centro de Investigaciones y Estudios Superiores en Antropología Social, Biblioteca Lorenzo Boturini Insigne y Nacional Basílica de Guadalupe, 2001), 150–151.