THE IMPERIAL WAY OF THE INCAS.

Of the big civilizations of the New World, the Maya, one of the first in Middle America, had to cut its way out of the jungle. The Aztecs had to conquer their way through Mexico. Far to the South, other mighty civilization, the Andean, thrust upward through some of the world's most forbidding terrain: the towering mountains and desert coast of Andean Peru.
The Inca Empire, which crowned these early civilizations of the Southern half of the globe, ruled from a capital 11,152ft/3,400m  in the clouds, near the Urubamba Valley of the Andes, Peru.
The Andean civilization centered far more than that of Middle America on the material techniques of life: - Planning big cities and irrigation works, - Building highways and a network of communications, and - Perfecting the domestic arts of weaving and pottery making.
The Inca passion for organization in every field extended even to their art work. The best in Andean art was produced by the Andean peoples who preceded the Incas and they simply absorbed and perfected the technique.
Civilization around the world traces their origins to the time when men settled down and started cultivating rather than hunting their food. The early people of South America showed a versatile talent for domesticating plants, many of them unknown in the Old World. Some 5,000 years ago they were already cultivating squash, peppers, gourds, beans, and cotton on the Coast of Peru.
By the time of the European invasion, these early people of South America were already better farmers that their Europeans contemporaries. They had domesticated the potato, the corn, the tomato, the yam, and the lima beans. They found a source of wool by taming the llama and the alpaca. They terraced the mountainsides and built vast irrigation systems.
Since very ancient time Pre-Inca civilizations of the Central Andes occupied an area, at over 4,000 m of elevation, which today is regarded as marginal for many basic crops. The ancient People of the Andes were able to build a dense population that supported both a city life and a highly organized social and economic society as evidenced from archaeological findings. Part of it lie in the type of agricultural technology employed, together with the choice of food plants, which together ensured both quantity and quality of sustenance. A strong economic base was in existence from at least 2000 years before the present time.
The extensive agricultural cultivation and irrigation system still work today and produce just like they did long time ago. The vast majority of these agricultural terraces are built on the sides of mountains and hills, and required hard work for creation, but ensured food production over a long period of time.  The reason for creating stepped agricultural fields are various. For example, the Sacred Valley region, in which the Vilcanota River, the main artery of life,  flows surrounded by abrupt mountains that are over 4000 m high, the sun's rays don't reach deep enough in the Valley, which remain cooler in their bottoms. Then the mountain sides ensure more intense sunlight for longer time during the day. In some parts there is little space in the Valleys, so the usage of steps actually increases the area available for agriculture.
The benefits of the steeped technology included defense against landslide and floods. In this way the water did not accumulate and run down over the towns below. The rocks used for creating the steps strengthened the sides of the mountains, that protecting what was in the Valleys from possible mudslide during heavy rainfall. Higher grounds protected the plantations from disasters.
The Vilcanota River is terrifying when its affluent and intense rain increase its volume. During the glorious period of the Inca Empire, the Sacre valley of the Vilcanota River was one of the most agriculturally productive region of the world. When Europeans waited for the rain to come, the incas were controlling the irrigation of the terraces by diverting small quantities of water from mountain rivers, making a sort of balance in the ecosystem of the land. The threat of drought was practically eliminated.
Up to this point in history, no culture in the world had spread a civilization over a similar terrain conditions like the whole of Peru's arid Coasts and High Mountains.