Final answer:
The Inca Empire once spanned regions currently part of Peru, Ecuador, Bolivia, Argentina, and Chile, with an economy based on trade of goods and services and unique infrastructure adaptations in the Andean terrain.
Step-by-step explanation:
The countries which have regions that were once part of the Inca Empire are Peru, Ecuador, Bolivia, Argentina, and Chile. The Inca civilization, which flourished in pre-Columbian America, established a powerful empire across this range, characterized by monumental buildings and an extensive road system that facilitated travel across the diverse and challenging Andean environment. The empire's economic system was unique, as it was based on trading goods and services without the use of currency, and the Incas managed their lands using terraced hillsides to overcome the harsh terrain. Spanning from Quito in Ecuador to northern Chile, the Inca Empire's unity and control over such a vast territory represented an impressive accomplishment in the history of the Americas.