Yeah. The Aztecs, according to the writings of Cortez, had light sources at night that didn't produce heat. Later, it was discovered they also had performed successful brain surgeries. Although by today's standards their tools were primitive, they also had a great deal of technology and knowledge which was lost as Cortez also burned all their books and writings that he could find.

Granted the Aztecs and Incas as civilizations were already in decline when the Spanish arrived, but a lot of knowledge was lost when they were conquered.