'Arabs and Persians are considered "Caucasion"'
Well, Arabs are considered Semitic. Their language is not in the Indo-European family.
Many Caucasions, Hungarians, Finns, Estonians and others speak Uralic-Altaic languages. The heavy hitters in that group are Turkish and Korean.
Caucasion relates to the presumed geographical "origins" of white folk. Indo-European deals with a family of languages which may or may not share Caucasion "origins".