So let's focus on the Inca Empire, but keep it in comparison to some of the other significant empires and civilizations we know about. So as we enter into the 15th century, we have the Kingdom of Cusco. What we now call the Inca Empire did not exist yet. The ninth ruler of the Kingdom of Cusco, a gentleman by the name of Pachacuti, he decides to go on a fairly aggressive effort of expansion and it is Pachacuti that takes the Incas from the Kingdom of Cusco and creates an empire. Now as I mentioned, they did not call themselves the Incas. Inca was actually their word for ruler, so this was Pachacuti Inca. Their name for the empire that gets started by Pachacuti was Tawantinsuyu, and what it's really referring to is the four regions, and you can see the four regions here that were conquered with Cusco at the center.