I discussed a lot of the various kinds of infrastructure in another question on the Inca Empire (Tawantinsuyu) posed yesterday - this would include state-owned pastures, royal estates, agricultural terrace systems, road systems, waystations, garrisons, and administrative centers of artisanship or imperial socialization. Maintaining these required immense amounts of labor, which the Incas required as a tax (typically considered "corvee" so not *technically* a tax for those who want to get semantically in the weeds); this social arrangement was known as the mita and was likely established in some societies before Inca hegemony. Additionally, communities who refused Inca rule were, on their subjugation, cast to the four winds (well, four quarters of the empire) - turned into mitmaqkuna, forcibly resettled into Inca-designed settlements or put to work in estates as retainers.

However, if we consider slavery to mean that people were considered property and could be bought, sold, or traded...we don't see any direct evidence of that kind of behavior in the empire. None of the relationships the Inca called mita and mitma (or even the Inca-subsidized administrator- or worker-for-hire, the yanakuna) were classified or considered slavery as such.

With all of that said, slavery was not unheard of in the Andes - or rather, in Amazonian communities. Raids between communities could have territorial implications of sovereignty, but they also served to capture men and women, whose lives were forfeit if they were taken captive. Some groups like the Yanomamo would kill men they encountered in raids while taking women and children. The person's life-force was now subservient to those who took it, and they could very well be killed (with their life force concentrated into a trophy head or shrunken tsantsa head as the Shuar call it, especially for warriors). However they could be expected to bear children, though often in a subservient role (as in the Tupinamba of the Brazilian coast). Women taken were often secondary wives to their husbands, more likely to be beaten or cast out as witches.

In the more distant archaeological past, it is difficult to discern slavery from other forms of servitude - numerous Moche vessels of the north Peruvian coast depict captives; as do older Chorrera vessels of the Ecuadorian coast. Nasca trophy heads have preserved on that dry southern coast; and Jama-Coaque vessels from Ecuador also depict trophy heads worn as necklaces. Were these captives slaves? Were they considered property? It's difficult to say for sure.

Further reading on slavery, with an eye toward Amazonian examples:

Bowser, Brenda J.
2008 Captives in Amazonia: becoming kin in a predatory landscape. In Invisible Citizens: Captives and their Consequences, pp. 262–282. University of Utah Press, Salt Lake City.

Cameron, Catherine M.
2016 Captives: How Stolen People Changed the World. U of Nebraska Press.