Why are most of the East Indians that I see in the USA very dark complected?

I mean no disrespect. I am African American and therefore at home with a rainbow of shades. I am always interested in different cultures and I like to people watch. I see those in the Latino culture come in every different shade. Even those who are Chinese or Japanese have varying shades of light and dark within their own spectrum. However when ever I see an immigrant of East Indian descent they are always those East Indians who are of the darker shades. The country has over a billion people and I know the skin shades must run the full color spectrum, yet over here in the USA I only see the darker ones. I never see someone with the complexion of Aishwarya Rai. The reason why I am asking is because I am curious if this is indicative of a cultural phenomenon that grew from the caste system....meaning perhaps its not so comfortable for those of a certain shade and this makes them much more comfortable with immigrating to a place where they don't have to deal with those specific issues