There is no such thing as "caucasians" referring to "white" people in Europe, which is why the other 3 people responding have no clue what you mean.
Considering a "white" person caucasian is an US- American invention and really complete nonsense.
The Caucasus is a REGION located at the north-west of Asia Minor, between Black and Caspian Seas. Tens of millions of years ago the Mediterranean, Black and Caspian Seas comprised one waterspace and the contemporary Caucasian ridge was the sea bottom. [See map link below]
So the CAUCASUS is a REGION and it has been - over centuries - inhabited by nations of Iberian, Indo-European, Semitic and Turk origin... None of them being most people's idea of "white" in the classical sense, by the way.
Personally I have lived on 4 continents and have visited 2 more...
And I had to come to the USA to first encouter this word and its odd use.
Anyhow:
When it comes to "white" people in Germany (which I'm assuming you're asking), the population is made up of the following groups:
German 91.5%
Turkish 2.4%
Other 6.1%
(last group largely made up of Greek, Italian, Polish, Russian, Serbo-Croatian, Spanish nationals)
Another thing I'd like to point out is that - other than Americans - Germans and Europeans in general think much less in "race" but rather in nationality. Looks are secondary to where a person was born. There are "Germans" of any colour nowadays. =)