Herbert Spencer is often remembered for his passionate belief in Social Darwinism. Social Darwinism is the belief that the biological theory of natural selection can be used to explain geopolitics and the differences between western nations and the rest of the world. It was used to reinforce the legitimacy of European imperialism in the second half of the nineteenth century and early twentieth century.

Almost all of the ruling dynasties of Persia (Iran) over the last 1000 years have been of Turkic origin. The Pahlavi dynasty, which took power in 1925, ended this long pattern.