In the song "Buffalo Soldier", what is the comparison between the dreadlock rasta and the buffalo soldier?

I'm doing an ysis on "Buffalo Soldier" by Bob Marley, and I know all there basically is to know in 3 hours of researching on Buffalo Soldiers, but I still am having a hard time really understanding the link between the Buffalo Soldier and the Dreadlock Rasta. I mean, they both were descended slaves from Africa. they are both fighting to get rid of oppression in a way. But I still am unsure of what Bob was trying to say about both of them... anyone help?