Well, right. Because Kurdistan--such as it is--is a region defined by the ethnicity of a people who live within the political borders of the aforementioned three countries. And BTW, the same is true of Kazakstan, Tajikistan, and Turkmenistan.

And for the one person reading who might actually find this interesting, "kazak" is the Central Asian (probably Urdu; I'm not sure) word for "gypsy" or "nomad" and kurd (or kord) is the Persian word meaning the same thing.