Texcoco (Aztec site) in the context of Codex Osuna

Aztec warfare concerns the aspects associated with the military conventions, forces, weaponry and strategic expansions conducted by the Late Postclassic Aztec civilizations of Mesoamerica, including particularly the military history of the Aztec Triple Alliance involving the city-states of Tenochtitlan, Texcoco, Tlacopan and other allied polities of the central Mexican region. This united the Mexica, Apulteca, and Chichimeca people through marriages.

The Aztec armed forces were typically made up of a large number of commoners (yāōquīzqueh [jaː.oːˈkiːskeʔ], "those who have gone to war") who possessed extensive military training, and a smaller but still considerable number of highly professional warriors belonging to the nobility (pīpiltin [piːˈpiɬtin]) and who were organized into warrior societies and ranked according to their achievements. The Aztec state's primary purpose was political expansion and dominance of and exaction of tribute from other city-states, a purpose that relied on constant warfare. Aztec society was also centered on warfare: every Aztec male received basic military training from an early age and one of the few possible opportunities of upward social mobility for commoners (mācehualtin [maːseˈwaɬtin]) was through military achievement, especially the taking of captives (māltin [ˈmaːɬtin], singular malli). Thus only specifically chosen men served in the military. The sacrifice of war captives was an important part of many of the Aztec religious festivals. Warfare was thus the main driving force of both Aztec economy and religion.

Nezahualpilli (Nahuatl for "fasting prince"; 1464–1515, modern Nahuatl pronunciation) was king (tlatoani) of the Mesoamerican city-state of Texcoco, elected by the city's nobility after the death of his father, Nezahualcoyotl, in 1472. Nezahuapilli's mother was Azcalxochitzin, who married Nezahualcoyotl after the death of her first husband, King Cuahcuauhtzin of Tepechpan.

Like his father, he was a poet, was considered a sage, and had the reputation of being a fair ruler. Only one of his poems survives: "Icuic Nezahualpilli yc tlamato huexotzinco" ("Song of Nezahualpilli during the war with Huexotzinco"). His court was a haven for astronomers, engineers, and soothsayers. During his reign, he abolished capital punishment for a number of crimes and struggled to keep the political independence of Texcoco during the increasing centralization of Aztec power in Tenochtitlán.

Nezahualcóyotl (Spanish pronunciation: [sjuˈðað nesawalˈkoʝotl]), or more commonly Neza, is a city and municipal seat of the municipality of Nezahualcóyotl in Mexico. It is located in the state of Mexico, adjacent to the east side of Mexico City. The municipality comprises its own intrastate region, Region IX (Mexico State).

It was named after Nezahualcoyotl, the Acolhua poet and king of nearby Texcoco, which was built on the drained bed of Lake Texcoco. The name Nezahualcóyotl comes from Nahuatl, meaning "fasting coyote". Nezahualcóyotl's heraldry includes an Aztec glyph as well as a coat of arms. The glyph depicts the head of a coyote, tongue outside the mouth with a collar or necklace as a symbol of royalty (one of the ways of depicting the Aztec king). The current coat of arms, which includes the glyph, was authorized by the municipality in the 1990s.