Blame it on Jim Crow
www.indiancountry.com/content.cfm?id=1065119255 - 32k
At this, is a article. about a Professor of Sociology Thomas Brown. he alledges that Wesorts Piscataway -Lumbee s have always claimed to have been seperate from African Americans
which is part of the claim of being Indian.
But said look at the records this seperatness developes during the Jim Crow period ,after the cival war. before that you see extensive intermarraige within the Black community.