One of the things Westerners like to do about non-Western civilization is deny their sophistication by pointing to some non-local antecedent/inspiration. The most notable iteration of this mind set is the persistent attribution of New World civilization to either alien, western or eastern inspiration. For example, the Nazca lines
are often described as being the product of some "unknown civilization," a line of argument suggested in the wikipedia entry itself. But even the earliest observers recognized a relationship between the pre-Incan civilization of the Nazca area and the Tiwanaku civilization of Bolivia/Southern Peru. However, the insistence that these lines are alien inspired is ridiculous. The Tiwanaku civilization developed on or near the Altiplano of Bolivia- a region that looks a lot like the place where the Nazca lines are located. The Tiwanakus were building temples and statues and junk like that BEFORE the Nazca lines were inscribed in the desert.
The idea that these lines couldn't be created from the ground is also ridiculous- anyone who has looked out a second story window at one point in their life would be competent to direct their creation. The fact is...these Tiwanakuns- they had potatoes- before anyone else in the world. They cultivated coca. Both of those items were inherited by the Incans. You look at the impact of the potato and cocaine/coca leaf on the world TODAY. It's impressive.
It seems more reasonable & respectful to just credit the Andean region for creating one of the world's autochthonus civilizations. There aren't that many places in the world where civilization began independently. Also, if you take the general spreading out of the human race from Africa through Asia to the new world, the Andean Civilization was the last, chronologically, to "get in place." Thus, when we look at the Incans, it's like looking at an analogous time in the ancient world of the Middle East, Egypt or India.
So drop all the crazy hocus pocus about the Nazca lines, Aliens and the Incas. You don't need that shit to make it relevant. The reality is more interesting.