The total area colonized was probably in the neighbourhood of 30,000 acres, and Tenochtitlán, the Aztec capital, depended on these lands for much of its food. By a comparable method, much of the waterlogged lakeshore plain was also converted into agricultural land. Particularly notable is the fact that all of these techniques of food production were achieved by human power and simple hand tools.
Aside from agriculture, the basin had a number of major resources, some of which were exploited not only for local consumption but also to supply other areas of Meso-America. Obsidian, natural glass of volcanic origin, was a superb material for a great variety of stone tools; and the northeastern ranges of the basin contained one of Meso-America’s major deposits. Basalt for manos and metates (milling stones) was also abundant. Lake Texcoco was a major source of salt, and the lakes generally provided waterfowl, fish, and other aquatic foodstuffs. The great pine forests above the limits of agriculture were a major source of lumber. On the other hand, the basin, because of its high elevation, was unsuitable for a great variety of tropical products, including cotton, paper, tropical roots and fruits, tobacco, copal incense, rubber, cacao, honey, precious feathers and skins, and such prized goods as metal, jade, and turquoise. The major motivation of Aztec conquest was to obtain control of these resources. Social and political organization
Aztec technology differed little from that of other Meso-American groups. One of its distinctive aspects was differentiation by status levels. The use of most of the extra-local resources noted above was limited to a small upper and middle class; and there were striking differences in dress, housing, and diet by social class. Commoners, for example, wore clothing woven from maguey fibre, while the upper classes wore cotton garments. The use of imported foods, at least on a regular basis, was limited to the upper and middle classes. Commoners lived in small adobe or stone and mud huts, the upper and middle class in large multiroomed palatial houses of cut stone, lime plaster, and concrete.
Aztec social and political organization can be divided into a number of levels of increasing size and complexity of organization. The nuclear family—that is, a pair of cohabiting adults and their unmarried children—formed the lowest level of organization. The nuclear family functioned in procreation, education of children, and as a unit of food preparation and consumption, with a well-defined division of labour between husband and wife. Among the Aztec, however, a number of nuclear families usually resided together in a single cooperating household, or extended family. Such a family usually consisted of a man, his married sons or brothers, and their families. The average peasant household of this type was small. Up to three nuclear families occupied a small multiroom house divided into apartments for each family. The houses were usually placed within a courtyard fenced with organ cactus or adobe walls, forming a compound. The extended family household probably functioned as a unit of land use and food production. In the towns, however, some households could be considerably larger, and the household of Montezuma II included several thousand people.
A number of households, varying from a few score to several hundred, were organized into an internally complex corporate group referred to as a calpulli by the Aztec and translated as barrio (“ward”) by the Spaniards. Questions about the structure and function of this level of Aztec organization have caused a great deal of debate among Meso-American specialists. It is clear, however, that it was a physical and territorial unit as well as a socially organized one. It was a unit of land tenure. Calpulli lands were owned communally but were distributed among various households. The household retained the right of usufruct, but only the calpulli as a whole could sell or rent lands.
The calpulli rural communities varied considerably in physical appearance. Some were isolated, tightly nucleated physical settlements surrounded by their agricultural land, whereas in others houses were dispersed through the land holdings. In a few cases, they were physically attached as wards to one or more other calpulli. These differences corresponded to ecological, economic, and political factors. Rural, dispersed settlements were found on terraced hillsides in which houses were tightly integrated with the terrace; in the chinampa area, each house was placed on its chinampa holding. On the other hand, nucleated, isolated calpulli were found in areas of level land, and the ward type was usually found in the towns and cities. In the latter case, many lost their agricultural character and became units of craft specialization. The calpulli was a unit of political administration within the larger unit that will be referred to here as the state. It was ruled by a council of household heads presided over by a chief selected by the council from within a particular lineage. The calpulli functioned as a unit of taxation to the central government, as a unit of corvée labour, and as a military regiment.
The structure of the calpulli is open to question. Some sources call it a kin group, “a lineage” with a common ancestor; and as a result some anthropologists have referred to it as a clan, or sib. There is no evidence, however, of either exogamy or unilineal descent; in fact, marriage records from the post-conquest period show a strong tendency toward endogamy. There is some evidence of internal ranking and significant status differentiation, another non-clanlike feature. The sources also mention smaller territorial subdivisions, referred to as barrios pequeños, or “little wards.” If these are descent lines, then the calpulli resembled quite closely a type of kin group called by anthropologists a ramage, or a conical clan. This is a group with a myth of common descent, divided into ranked senior and junior lineages based on the seniority of older versus younger brother in the group genealogy. In support of this reconstruction is the statement that the calpulli god was a deified ancestor.
The calpulli also functioned as a unit of education, for each possessed a school for young men—the telpuchcalli—primarily for military and moral instruction.
Above the level of the calpulli was the state. With the exception of those historical periods when larger polities, such as the Aztec empire, emerged, such states in Meso-America, including the Basin of Mexico, were small. Just prior to the Aztec expansion there were 50 or 60 such states in the basin, with an average size of about 50 to 60 square miles. In 1519 these once independent domains had an average population of 25,000 to 30,000 people. In less densely settled areas, the territories were larger and populations smaller. The range of size was from a few thousand up to 100,000.
The average small state included a central town with a population of several thousand, the balance of the population consisting of the rural calpulli. The central town was divided into wards that corresponded in size and to a certain degree in structure to the rural calpulli but were clearly different in function; they in turn were divided into barrios pequeños. At the head of the state was an official called the tlatoani, to whom all household heads owed allegiance, respect, and tax obligations. The tlatoani’s position was fixed within a particular lineage, the particular choice varying from state to state. In some areas, succession passed from father to son; in others, the succession went through a series of brothers and then passed to the eldest son of the eldest brother. In still other states, the office was elective, but the choice was limited to sons or brothers of the deceased ruler. The office was accompanied by all of the trappings and sumptuary behaviour typical of despotic states. The ruler resided in a large, multiroom masonry palace inhabited by a great number of wives, servants, and professional craftsmen. He was carried in a sedan chair in public and treated with exaggerated respect by his subordinates. The tlatoani held considerable power: he appointed all lesser bureaucrats, promoted men to higher military status, organized military campaigns, and was the distributor of booty and tribute; he collected taxes in labour, military service, and goods from his supporters; he owned private estates manned by serfs; he was the final court of appeal in judicial cases; and he was titular head of the religious cult and head of the town market.