It promoted the (relatively) rapid diffusion of immigrants, language, and domesticated crops and animals. Those factors are examined in excellent detail in Jared Diamond's book, "Germ, Guns and Steel" which I highly recommend for anyone studying the development of world cultures. It's a long read, but well worth it.
Sumerians built ziggurats because they believed that they would be more closely connected to the heavens. They believed that ziggurats connected the earth and the heavens.
The conquest of Mecca was the conquering of the town of Mecca by Muslims led by the Islamic prophet Muhammad in December. The conquest marked the end of the wars between the followers of Muhammad and the Quraysh tribe.
