It does not say on the wiki but I think that the dwarves on Green Bit are losely based off of Native Americans. In OP after the Donquixote leaves Dressrosa after 100 years of mistreatment the Dwarves were given Green Bit as retribution just like how the Indian's got reveres. They also have history going back to before the void century and came to Dressrosa and cutivated it lIke how the natives came via the ice bridge to North America. And I don't know about in the states but in Canada there is an agreement that someone who is of Native decent is able to get a lesser punishment or jail sentence because they are native. Just like how the dwarves can take anything they want without consequences.