These people became conquerors because (as Chapter 10 tells us) agriculture and technology could diffuse much more easily along an east-west axis than across a north-south axis. Crops can easily move east to west because areas at the same latitude generally have similar climates and similar crops can grow in those places. This means that more civilizations can arise because they do not have to independently invent agriculture. As more civilizations arise, they can invent technology and pass it along to one another. These sorts of advantages made it more likely that Eurasians would become the dominant force in the world.