1) Being Arab isn't a race, it's an ethnicity.
2) Arabs ARE Caucasians. While there's an infinite amount of debate in the scientific community over whether there actually ARE any races, or how many there are, there's generally accepted to be 3 or 4, and they ain't Asians, nor Amerindians, and only some are Negroid or partially Negroid.
Aren't Jews and Arabs both Semites?