Dominican Republic always had somewhat similar demographics to Today. Spain's interest in plantation slavery was always limited compared to the rest of Western Europe, so the DR ended up mostly mixed race instead of black. Until somewhat recently, the DR had a much smaller population than Haiti (Higher Birthrates in the DR led to a catching up). The DR's opposition to Haiti has always been through Ethno-Racial reasons, Cultural Differences plus Dominican Mixed Race people led to the independence movement in the DR.