In the game I have successfully conquered all of Africa, and still had limited and positive interactions with other nations including the Roman, Indian, and other empires. My goal was to first focus on conquering all Africa, then to expand by either traveling across the Atlantic Ocean to the Americas or to travel to Australia. In order to efficiently and successfully conquer all of Africa I first had to produce many settlers to start new cities. Once I created the new cities I wanted first I wanted to develop military protection for each of my cities and then I wanted to culturally expand the city.
My first city, Coach, was developed on the top right corner of Africa. Then I started to expand and without even realizing that my settlers expanded on the east and west axis of Africa. When I did realize this, I began to send my settlers to the south; however, the process of developing these cities took much longer then the easily develop cities on the upper portion of the continent.
Diamond goes on to discuss that the main reason that the spread of civilization is so easy and fast on the east-west axis is because that along that axis is the same climate, day length, and type of animal life. He continues to relate this to the ability of Eurasia to develop so quickly and its ability to conquer other nations including the Incas in South America and other nations in Africa.