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.
Nobody chooses the rulers. If its through a system of heredity, when the rulers die their children take over.
Because they couldnt stop discrimination from happening
Answer:
The long border between the two countries means that peace and security in that region are important to the U.S.'s national security and international trade. The U.S. is Mexico's biggest trading partner and Mexico is the U.S.'s third-largest trading partners.
