The Incas have begun carving out an empire amid a harsh environment in the Cuzco region of the southern Andes by 1200.

Using stone hoes and digging sticks with a footrest for pushing the end into the soil, the people of the Inca civilization skillfully construct terraces, irrigation, and drainage system, fertilizing the land and building stone storehouses to preserve food.

Cultivating such foods as corn, white and sweet potatoes, and squash, the Inca have domesticated the llama as a beast of burden and keep alpacas for wool.

The Andean Inca culture, centered upon the Cuzco region, has domesticated the llama as a beast of burden and keeps alpacas for wool.

They cultivate such foods as corn, white and sweet potatoes, and squash.

Using stone hoes and digging sticks with a footrest for pushing the end into the soil, the Inca culture skillfully constructs terraces, irrigation, and drainage system, fertilizing the land and building stone storehouses to preserve food.

Bronze is apparently in use in Bolivia.

Ecuador offers little archeological evidence of its pre-Hispanic civilizations.

Nonetheless, its most ancient artifacts—remnants of the Valdivia culture found along the coast north of the modern city of Santa Elena in Guayas Province—date from as early as 3500 BCE.

Other major coastal archaeological sites are found in the provinces of Manabi and Esmeraldas; major sites in the Sierra are found in Carchi and Imbabura provinces in the north, Tungurahua and Chimborazo provinces in the middle of the Andean highlands, and Cafiar, Azuay, and Loja provinces in the south.

Nearly all of these sites are dated in the last two thousand years.

Large parts of Ecuador, including almost all of the Oriente, however, remain unknown territory to archaeologists.

Knowledge of Ecuador before the Spanish conquest is limited also by the absence of recorded history within either the Inca or pre-Inca cultures as well as by the lack of interest taken in Ecuador by the Spanish chroniclers.

Before the Inca conquest of the area that comprises modern-day Ecuador, the region is populated by a number of distinct tribes that speak mutually unintelligible languages and are often at war with one another.

Four culturally related native groups, known as the Esmeralda, the Manta, the Huancavilca, and the Puna, occupy the coastal lowlands in that order from north to south.

They are hunters, fishermen, agriculturalists, and traders.

Trade is especially important among different coastal groups, who seem to have developed considerable oceanic travel, but the lowland cultures also trade with the peoples of the Sierra, exchanging fish for salt.

The Sierra is populated by elements, from north to south, of the Pasto, the Cara, the Panzaleo, the Puruha, the Canari, and the Palta cultures.

These people live mostly on mountainsides and in widely dispersed villages located in the fertile valleys between the Cordillera Occidental (Western Chain) and the Cordillera Oriental (Eastern Chain) of the Andes.

The Sierra natives are a sedentary, agricultural people, cultivating corn, quinoa, beans, and many varieties of potatoes and squashes.

The use of irrigation is prevalent, especially among the Cañari.

A wide variety of fruits, including pineapples and avocados, is grown in the lower, warmer valleys.

Historians believe that political organization centered around local chieftains who collaborated with one another in confederations or were subjected to "kings."

Such local chiefs have considerable authority; they can raise armies, for example, and administer communal lands.

A severe twenty-three-year drought begins in 1276 to affect the Grand Canyon area; it will eventually forcing the agriculture-dependent Pueblo III culture to migrate out of the region.

It is not known when the earliest humans reached what is now Colombia.

The oldest evidence of occupation, which is pending confirmation, dates from before twenty thousand BCE, at sites in the central Andean highlands, but the first native peoples undoubtedly arrived earlier, coming presumably by way of the Isthmus of Panama.

Over succeeding millennia, there are further migrations and mutual cultural influences between different geographic regions of Colombia and not just Central America but the Caribbean, coastal Ecuador, and the Amazon region.

It is likely that settled, partly agricultural societies first arose in the northern Caribbean lowlands of Colombia by the second millennium BCE.

No single dominant native culture has emerged.

Rather, most of the original Colombians belong to one or another of three major linguistic groups—Arawak, Carib, and Chibcha—and comprise a patchwork of separate cultures and subcultures.

These indigenous peoples develop the cultivation of yucca in the lower elevations, maize at middle altitudes, and potatoes in the highlands.

They practice ceramic pottery and other crafts, with impressive achievements in the working of gold from alluvial deposits, and by the time of the Europeans' arrival, they generally display  the beginnings of both social stratification and a political system on the basis of chieftainships.

By contrast, Colombia's Muiscas—based in the present departments of Cundinamarca and Boyaca in the Cordillera Oriental—live in dwellings scattered through the countryside, and their temples and palaces are of perishable materials, but Muiscas, of whom there are perhaps six hundred thousand, are far more numerous than the Taironas and cover a wider territory, extending from the area of present-day Bogota northeastward to Tunja and beyond.

As in the case of the Taironas, Muisca local chiefdoms have consolidated into two separate confederations.

The Muisca territory also includes Laguna de Guatavita, site of the fabled ceremony of El Dorado, the gold-dusted dignitary who plunges into the crater lake along with a rain of golden offerings.

More than any other native people, the Muiscas have served as a model for later ideas of Colombia's pre-Columbian civilization.

The Incas of Cusco (Cuzco) originally represented one of the small and relatively minor ethnic groups, the Quechuas, that dot the central and southern Andes of Peru.

Gradually, as early as the thirteenth century, they began to expand and incorporate their neighbors.

Inca expansion is slow until about the middle of the fifteenth century, when the pace of conquest begins to accelerate, particularly under the rule of the great emperor Pachacuti Inca Yupanqui (1438-71).

Historian John Hemming describes Pachacuti as "one of those protean figures, like Alexander or Napoleon, who combine a mania for conquest with the ability to impose his will on every facet of government."

Under his rule and that of his son, Topa Inca Yupanqui (1471-93), the Incas come to control upwards of a third of South America, with a population of nine to sixteen million inhabitants under their rule.

Pachacuti also promulgates a comprehensive code of laws to govern his far-flung empire, called Tawantinsuyu, while consolidating his absolute temporal and spiritual authority as the God of the Sun who rules from a magnificently rebuilt Cusco.

Although displaying distinctly hierarchical and despotic features, Incan rule also exhibits an unusual measure of flexibility and paternalism.

The basic local unit of society is the ayllu), which forms an endogamous nucleus of kinship groups who possess collectively a specific, although often disconnected, territory.

In the ayllu, grazing land is held in common (private property does not exist), whereas arable land is parceled out to families in proportion to their size.

Because self-sufficiency is the ideal of Andean society, family units claim parcels of land in different ecological niches in the rugged Andean terrain.

In this way, they achieve what anthropologists have called "vertical complementarity," that is, the ability to produce a wide variety of crops—such as maize, potatoes, and quinoa (a protein-rich grain)—at different altitudes for household consumption.

The principle of complementarity also applies to Andean social relations, as each family head has the right to ask relations, allies, or neighbors for help in cultivating his plot.

In return, he is obligated to offer them food and chicha (a fermented corn alcoholic beverage), and to help them on their own plots when asked.

Mutual aid forms the ideological and material bedrock of all Andean social and productive relations.

This system of reciprocal exchange exists at every level of Andean social organization: members of the ayllus, curacas (local lords) with their subordinate ayllus, and the Inca himself with all his subjects. Ayllus often form parts of larger dual organizations with upper and lower divisions called moieties, and then still larger units, until they comprise the entire ethnic group.

As it expands, the Inca state becomes, historian Nathan Wachtel writes, "the pinnacle of this immense structure of interlocking units. It imposed a political and military apparatus on all of these ethnic groups, while continuing to rely on the hierarchy of curacas, who declared their loyalty to the Inca and ruled in his name."

In this sense, the Incas establish a system of indirect rule that enables the incorporated ethnic groups to maintain their distinctiveness and self-awareness within a larger imperial system.

All Inca people collectively work the lands of the Inca, who serves as representative of the God of the Sun—the central god and religion of the empire.

In return, they receive food, as well as chicha and coca leaves (which are chewed and used for religious rites and for medicinal purposes); or they make cloth and clothing for tribute, using the Inca flocks; or they regularly performed mita, or service for public works, such as roads and buildings, or for military purposes that enable the development of the state.

The Inca people also maintain the royal family and bureaucracy, centered in Cusco.

In return for these services, the Inca allocates land and redistributes part of the tribute received—such as food, cloth, and clothes—to the communities, often in the form of welfare.

Tribute is stored in centrally located warehouses to be dispensed during periods of shortages caused by famine, war, or natural disaster.

In the absence of a market economy, Inca redistribution of tribute serves as the primary means of exchange.

The principles of reciprocity and redistribution, then, form the organizing ideas that govern all relations in the Inca empire from community to state.

One of the more remarkable elements of the Inca empire is the mitmaq system.

Before the Incas conquer the area, colonies of settlers are sent out from the ayllus to climatically different Andean terrains to cultivate crops that will vary and enrich the community diet.

Anthropologist John V. Murra dubs these unique Andean island colonies ''vertical archipelagos," which the Incas adapt and apply on a large scale to carve out vast new areas of cultivation.

The Incas also expand the original Andean concept of mitmaq as a vehicle for developing complementary sources of food to craft specialization and military expansion.

In the latter instance, Inca mitmaq are used to establish permanent garrisons to maintain control and order on the expanding Inca frontier.

What "began as a means of complementing productive access to a variety of ecological tiers had become," in the words of Murra, "an onerous means of political control" under the Incas.

The Incas capture and destroy their largest remaining rival, the rich and powerful Chimu kingdom on the north coast of present Peru, in about 1470.

The Chimu capital, Chan Chan, declines rapidly after the Inca conquest of the region.