In the year 1438, an inevitable confrontation placed Incas and Hanan Chancas on the same battlefield. The bloody Hanan Chancas were feared because, if they won, certainly, the losers would be submitted to a macabre ritual of torture, where they would be slowly scalped alive. Then, their skulls would serve as goblets, from where the tormentors would drink their blood.
His fame made tremble all peoples, would not be surprising that they were respected in the extreme.

For the first time, Cuzco was in absolute danger, a simple slip and Inca people would be exterminated. Forty thousand men of war, led by Anco Huayllu, advanced to encircle the city.

 At that moment, panic had settled and Inca Wiracocha was forced to take refuge with the family and some nobles in Collasuyo. Everything seemed hopelessly lost.

However, the prince Cusi Yupanqui stayed, to defend the city, leading a resistance inspired both in the boldness of a diplomatic strategy to drive the enemy to an unlikely armistice, as in the audacity of the confrontation on the battlefield. First he tried to bring peace to the besiegers, trying to gain time to gather allies, meanwhile, tried to put into practice a desperate strategy.

Legend has it that, Cusi Yupanqui posted his army in Yawarpampa (Field of Blood) and while they were waiting for the enemy army, ordered to make mounds of stone that, at the distance, seemed to be soldiers and that the army was more numerous than really was.

Then, in the midst of battle, the mounds of stone have become real, by the will of the gods, giving to the Incas, the victory, both in battle and in war. This day died twenty-two thousand chancas and eight thousand people of Cuzco.

Perhaps history can explain the legend, suggesting that "the little mounds that became real soldiers" were just, the long awaited assistance requested by Prince Cusi Yupanqui, to the neighboring peoples, who have resolved to join the people of Cuzco in full battle, making it appear that the stones became alive.

That day, they were welcomed as heroes in the Plaza de Armas in Cuzco and the Prince came to power with the name of Pachacutec.