Famous Mexican-American comedian George Lopez once told a joke that, as they frequently do, made his whole crowd break down laughing -- but also inadvertently exposed its ignorance. In an attempt to demonstrate the foolishness of racial distinction, he asked
"Where is Caucasia?!"
Caucasia -- also sometimes referred to as The Caucasus, is the geopolitical region on the Eurasian supercontinent between the Black and Caspian Seas. It is also partly defined by its namesake mountain range; the Caucasus Mountains have for centuries been considered a division between Europe and Asia, and the states of Caucasia have been suspended between them for just as long.
Caucasia has two regions: Transcaucasus, the southerly, and Ciscaucasus, the northerly. Ciscaucasus is the more mountainous of the two, containing Mount Elbrus, which, at almost 19,000 feet in height, is sometimes called the highest point in Europe. Where the Ciscaucasus is not mountain it is piedmont; its development relative to that of Transcaucasus has been much retarded by its lack of social and political centrality. While it does not actually contain any whole, internationally-recognized independent states, the Ciscaucasus does contain districts of southwest Russia, the north of Georgia, and the north of Azerbaijan. Transcaucasus, on the other hand, is substantially more arable, and generally more conducive to domestication than its polar counterpart. It contains the whole of Armenia, and almost all of Azerbaijan and Georgia. The southern portion of the Caucasus Mountains absorb much of the untamed Transcaucasian landscape.
Now, let's make Mr. Lopez's question relevant. Why are ethnically "white" people -- Aryans, for instance, or northern Semites (like, Mountain Jew Semites, rather than African Semites) called Caucasian? Well, they are clearly named for a region, but as equally clearly they do not all come from there. While the etiology of this nomenclature is not certain, Continental scientists (particularly those Germans... crazy Germans... ) used to theorize a great deal about the origins of man (particularly in the late 18th century, well into the 19th), and the races that they had determined existed on earth. These theories were thrown all over the place, and they all influenced the others, such that eventually a conclusion had been reached that when Indo-European tribes had eventually become distinct from each other, Caucasia (and presumably the surroundings -- Turkey, Iran, et al) had become the home of the "white" race. I know that my explanation is sketchy as shit... But I don't really know what I'm talking about! Anthropologists and historians have been working for three hundred years to address the scientific issue of race, and they still haven't totally figured it out.