More precisely, their territory stretched along the west coast of South America from where now is Ecuador and Columbia to Chile on the other end.
Like the Romans, they unified their empire by building a network of roads to unite people from different cultures.
Incan civilization was first established around 1150 A.D. They expanded their territory through alliances and military conquests.
Divine right to rule
Incan people worshiped the sun. Their leader was called Sapa Inca. He was regarded as the son of the sun, and had absolute power. Whoever disobeyed the leader was punished by death or incarceration.
The rulers preferred to assimilate new regions to add them to their empire, over using military force to conquer them. Before taking any military action, the leaders of a land the Incas wanted where offered full rights of the empire. These included the right to govern under Incan guidance. The conquered tribe had to agree to worship the Incan sun god, and regard the Inca as the earthly representative of that god. Business and education had to be conducted in the Incan language.
Duties of citizens
All men between the ages of 25 and 50 had to serve in the army. Some men fought in wars, some worked on constructing new roads.
In return, the resources of the conquered lands were distributed throughout the empire, to support every part of the empire. Sons of defeated leaders were brought to the capital Cuzco, to learn the Incan way of life.
Commoners were not allowed to wear any clothes other than the one provided by the state. Everyone was given the same style of clothes, the style of which was determined by the leader of the empire. This clothes was to be worn until it ripped to the point the state would agree to provide a replacement.
Like most ancient religions, Incan religion deviated from the initial religion. They believed there was one supreme god, Viracocha, who created all the other gods. There were smaller gods for sun, moon, stars, thunder, rain, mountains, and many other things in nature. They worshiped their gods in some way at every point in their lives.
Their worship involved ritual prayers that could only be recited by trained priests. They also involved dancing and drinking. And they involved sacrifices. Depending on the occasion, different sacrifices were offered. Sometimes it could be handmade objects, made of textiles, gold, or silver. Other times it could be portions of the harvest or animals. During critical times, such as during famines, earthquakes, eclipses, or death and ascension of rulers, they believed gods were demanding child sacrifices.
During child sacrifices, a beautiful child would be taken, dressed nicely, well fed, and blessed by the people. Then they would take the child to the mountain top and kill them. It's likely the the children were given some drugs to chew to lessen their fear and pain.
So was the Jewish religion in the Old Testament that harsh? It depends on what you compare it to.
Like other ancient civilizations before them, Incas construction techniques were very sophisticated, and more advanced than ours in some respects.
Huge boulders of rock were used to construct structures. But these boulders were so refined to fit one another, that you couldn't put a thin knife's blade between the cracks. When the Incan structures in Machu PIcchu were discovered hundreds of years after they were built, the city was covered with vegetation, but no plant could find their way through the cracks between the rocks. These structures also withstood earthquakes for hundreds of years.
Roads built by Incas were found in remarkably good condition, withstanding the stresses of rain, wind, ice, and drought over hundreds of years.
These roads were used only for official government purposes, for trade merchants, army troops, and mail couriers.
Every mile or so, along the roads, was a mail post with two couriers. While one rested, the other was waiting for the call to deliver the next message or package. Sleeping through the call was punishable by death.
Mail service worked swiftly, delivering messages and packages up to 185 miles per day. And here's an example of how fast the mail service was working. When the emperor was living in the palace in the Cuzco capital, he had fresh fish delivered every day from a coast 155 miles away.
Emergency news were passed on through smoke signals.
When a region was too steep, instead of roads, the builders cut the steps up and over the mountains. Llamas and people could walk these steps to transport packages.
Incas lived in small families. Each family was allocated land and animals. Some food they produced was used for themselves. Some was given to the state. Redistribution of food across the empire fed millions of people with products of different climate regions.
The commoners were given grains, fruits, and vegetables to eat. Meat and fish were usually reserved for the higher class.
The local tribes were skilled at crafting different objects. When a tribe was conquered by the Incas, they were encouraged to share their skills and techniques with the rest of the empire.
Incas had no writing system. They used knotted cords to record information. Cords of different colors hung from the main thicker cord. Their position indicated the subject matter of the record. Different colors were used for 10s, 100s, 1000s, and 10000s. Census data, harvest results, storage capacities, were recorded in this manner.
The Incas had no monetary system. They considered textiles to be more valuable than precious stones delivered by conquered peoples. Their weapons and tools were made from ordinary copper and tin. Gold and sliver was reserved for the rulers, and sacrifices.