Caucasian (adj.) Look up Caucasian at
1807, from Caucasus Mountains, between the Black and Caspian seas; applied to the "white" race 1795 (in German) by German anthropologist Johann Blumenbach, because its supposed ancestral homeland lay there; since abandoned as a historical/anthropological term. (See Aryan).
Caucasian (n.) Look up Caucasian at
"resident or native of the Caucasus," 1843; see Caucasus + -ian. Meaning "one of the 'white' race" is from 1958 (earlier Caucasoid, 1956).