It is interesting you mentioned that.

I have heard many people talking about Indians value skin color, and that their caste system is more or less based on skin color as well. However, many Indian people I know, including some of those from prominent families, are in fact quite dark skinned. I am not exactly sure how it reconciles with what I have heard, and it is difficult to ask any ethnic Indian friends of this question. In any case, I indeed do not know of any Indians marrying people of African descent.