I am married to a man outside of my race. You ask for proof that Quran states that it is allowed - I think we should ask you - and you should ask whoever told you - for proof from Qur'an and Sunnah that its NOT allowed for a woman....whoever made the claim should back it up otherwise they speak wrongly of Islam. Adding to the deen is haram - simple as. The Prophet pbuh himself married women from different areas and tribes - is this not the perfect example for us that women and men can marry whomsoever they please as long as they are muslim. And the Quran states clearly who is allowed and not allowed for women to marry. It also states clearly:
Mankind! We created you from a male and female, and made you into peoples and tribes so that you might come to know each other. The noblest among you in Allah's sight is the one of you who best performs his duty. Allah is All-Knowing, All-Aware. (49:13)
and:
Say: 'If your fathers or your sons or your brothers or your wives or your tribe, or any wealth you have acquired, or any business you fear may slump, or any house which pleases you, are dearer to you than Allah and His Messenger and striving in His Way, then wait until Allah brings about His command. Allah does not guide people who are deviators.' (9:24)
.....which warns against those who take their 'tribe' ( or race) as more important than Islam...
It is also not for us to disprove the claim that women cant marry outside of race - it is for whoever made that claim to show proof - or have that view renounced as cultural and consigned to the rubbish heap. We are muslims - and a woman may marry any man who is Muslim - wherever he or she is from.
Wasalaams