Answer: Smallpox
Step-by-step explanation:
It is unknown when smallpox first appeared as a natural disease in prehistory. The fifth and seventh centuries saw the introduction of smallpox to Europe, and the Middle Ages saw repeated epidemics of the disease. The sickness had a significant impact on the rise of Western civilization.
The Spanish and Portuguese conquistadors imported smallpox, which was unknown in the New World. The epidemic wiped off the local population and contributed to the fall of the Inca and Aztec empires. Like this, early settlers brought the disease to North America's eastern coast, where it caused the native population to dwindle. One of the first instances of biological warfare was likewise inspired by the catastrophic consequences of smallpox.