De Soto's expedition spread Eurasian diseases into the interior of the country, inadvertently killing thousands of Native people.
Really Basic Explanation:
Hernando de Soto, obviously a European, traveled to Florida and explored around. While exploring around the Florida area, he came into contact with Native Americans. The Spanish carried a deadly disease called smallpox. Since the Spanish had already come into contact with smallpox before, they developed immunity. Unfortunately for the Indians, none of them had ever experienced a smallpox outbreak in their region. The new introduction to smallpox devastated the Native American population, and in certain tribes over 90% of the Native Americans died.
The Reason prohibition directly led to organized crime was because the public demand for illegal alcohol was increasing, therefore people such as Al Capone would organize secret bars called “speakeasies”