Before the Spanish set foot on the soil of Tahuantinsuyo, the epidemics had already advanced and had taken hold in the land with unusual violence. On the first voyage of Pizarro from Panama, perhaps on the island of La Gorgona or on the mainland, a white man and a black man fell ill and infected the local population. From there, it spread like wildfire, the sickness that spread uncontrollably, showing no mercy against innocent people in the face of those new diseases. These illnesses were eruptive diseases like smallpox, chicken pox, measles, etc., and the common cold. The native people were struck by diseases common in Europe but against which they had no genetic resistance. A fatal contribution from across the seas.

After the first devastation, the epidemics became recurrent. There were so many and appeared so often they annihilated entire ayllus. Thus we find in the zone of Huarochiri a list from the eighteenth century of some communities that disappeared due to illnesses. Next to the ayllus figures the word "finished".

Undoubtedly the epidemics weakened Andean resistance against foreigners and facilitated the invasion. According to estimates by the historian David N. Cook, the demographic fall reached up to the end of the sixteenth century, 90% of the prehispanic population and the disappearance of almost all of the inhabitants of the central coast affected directly by the civil wars between the Spanish, the excess of tribute and the building of the City of Kings.