the entire Western Hemisphere would come under the domination of European nations, leading to profound changes to its landscape, population, and plant and animal life. In the nineteenth century alone over 50 million people left Europe for the Americas. The post-1492 era is known as the period of the Columbian Exchange. The potato, the pineapple, the turkey, dahlias, sunflowers, magnolias, maize, chilies, and chocolate went East across the Atlantic Ocean. Smallpox and measles but also the horse and the gun traveled West.The European and Asian lifestyle included a long history of sharing close quarters with domesticated animals such as cows, pigs, sheep, goats, horses, and various domesticated fowl, which had resulted in epidemic diseases unknown in the Americas.The first conquests were made by the Spanish and the Portuguese. In the 1494 Treaty of Tordesillas, ratified by the Pope, these two kingdoms divided the entire non-European world between themselves, with a line drawn through South America.
