The Incas had less than one hundred years of glory, yet in this time this tribe from Cusco conquered a great number of regional states in South America. In the high point of the Inca Empire their southern border was the Maule River in Chile, and in the north the Ancasmayo River in Colombia. This Empire or Inca state was called Tahuantinsuyo.
We know from historical writing and the archaeological record that the Incas did not possess a written language, although, they must have used some symbols and perhaps diagrams. The Qhipu (a collection of colored strings and knots) was extensively used for accounting and record keeping. But Quipus need highly trained interpreters to read them, and the Spanish were unable to locate or interrogate even one of these specialists.
Before the Incas, in the country we know as Peru today, there had developed a wide range of local states that had a high level of culture, administrative and artistic development (Chavin, Paracas, Nazca, Mochica etc) including the Wari culture which expanded from the 7th to 10th century almost over all Peruvian territory.
There are a number of interesting "origin myths" about where the Incas came from, but most likely they were a tribe that came from the Lake Titicaca area. This tribe, were the Quechua people (and the name which is used to label the native language) and the head of the tribe was called the Inca. These days the name Inca refers to all pre Colombian societies in Peru, particularly to the conquering Quechua tribe. After some centuries, this group consolidated their power after defeating neighbouring tribes, and around 1438 the Inca state really came into power under the Inca Pachacutec.
The Inca Pachacutec began the expansion of his dominions by military and diplomatic means through reciprocal agreements with his neighbours - or outright conquer. All the achievements of the "Incas" were actually in place prior to the "Inca Empire" - fine rock construction, cultivation systems and irrigation, but what the Incas did was organise, administer and make a pan Andean state that brought together many warring tribes. The success of the reciprocal agreements and administration was based on a common economic system, a system of agricultural production, of redistribution of harvests, and of religion. It was a system that relied on the theocratic hierarchy of the sovereign Inca and his elite in Cusco, and that incorporated the nobility of the conquered states. In many cases, the Inca permitted nobles of other tribes to maintain the administration of their kingdoms.
Vital to Inca expansion was the construction of thousands of kilometres of roads that perfectly maintained communication between the different parts of the state. Also important was the unifying aspect of the cult of the sun, water and earth as central religious themes and the imposition of Quechua (or Runasimi) as the official language.
Tahuantinsuyo was divided into four parts (or suyos), which communicated with Cusco through a vast network of Inca roads. At the north east of Cusco was located Chinchasuyo, to the south east Contisuyo, to the north east Antisuyo, and to the south east, Collasuyo.
Inevitably this vast state over extended itself and began to decline with a war for the throne between the brothers Huascar and Atahualpa between 1524 and 1532. Both were sons of the Inca Huayna Capac, who died suddenly from a cold, a virus that had already arrived in South America from Europe with the first conquistadors.
The final blow to the Inca Empire was delivered by a small group of Spanish Conquistadors led by Francisco Pizarro who captured the Inca Atahaulpa (the winner of the war between the two Inca brothers) and later executed him. With the execution of the Inca in 1533, the Empire effectively collapsed.
Pizarro and the conquistadors took Cusco in November 1533, and the city remained intact for the following three years until the Spanish Puppet Inca, Manco Inca II amassed a huge Indian army of between 100,000 and 200,000 people and laid siege to Cusco for over six months which destroyed much of the Inca capital.
Manco Inca retreated to deep into the jungle at Vilcabamba where he continued to fight a guerrilla war, being assassinated in 1545 by members of Diego de Almagro faction, to whom he had given refuge in Vitcos. Manco Inca was not able to pass his fighting spirit on to his son Sayri Tapac, because the latter was apparently persuaded by his Cusco family members to side with the Spanish crown
After the death of Sayri Tapac, his brother Titu Kusi Yupanqui assumed leadership - he was baptised as a Christian and generally collaborated with the Spanish - dying of a mysterious illness.
Then Tupac Amaru, the younger brother, young and inexperienced, but an implacable enemy of the conquistadors came to power. The Spaniards, recognizing in his rebellious character the contrast with his brother's weakness, ordered his capture and pursued him to his the last capital of the Incas at Espirtu Pampa.
Tupac Amaru was beheaded in the plaza of Lima, in the presence of Viceroy Toledo on September 24, 1572, thus effectively ending the line of the Incas.