Firstly, your question is extremely vague. To answer what I think you're asking: Allah didn't just send it to Arabs, the message was given to all the world, but revealed to an Arab.
We have sent it down as an Arabic Qur'an, in order that ye may learn wisdom. (Qur'an: 12:2)
Thus have We sent by inspiration to thee an Arabic Qur'an: that thou mayest warn the Mother of Cities and all around her,- and warn (them) of the Day of Assembly, of which there is no doubt: (when) some will be in the Garden, and some in the Blazing Fire. (Qur'an: 42:7)
And this is a Book which We have sent down, bringing blessings, and confirming (the revelations) which came before it: that thou mayest warn the mother of cities and all around her. Those who believe in the Hereafter believe in this (Book), and they are constant in guarding their prayers. (Qur'an: 6:92)
These verses should explicate the fact that although the message of the Qur'an was sent to an Arab, it was directed towards all of mankind. Hence, Allah beginning many verses saying, "O Mankind!" (whether you are Muslim or not) and "O You who believe!" as compared to "O Arabs!"
Does this make sense? Or do you need further elaboration?
I'm not a scholar so there is a plethora of other information that can explain this matter in more detail. I'll try to post some things if I find them...