The three rules known for unifying Japan are Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu.
For example humans: Geography not only defines whether humans will survive in a given region, but it also determines people's lifestyles as they adapt to the food and climate patterns available.
I think the voyage of Amerigo Vespucci was the most important because it showed all of Europe that what Christopher Columbus thought was the indies was actually new undiscovered land.
THE PRESIDENT'S CONSTITUTIONAL DUTY TO FAITHFULLY EXECUTE THE LAWS. :)