Complex sentence: Spain imported the dye from its colonies in South America, and it was a major crop in Haiti and Jamaica, with much or all of the labor performed by enslaved Africans and African Americans.
Split into simpler sentences: Spain imported the dye from its colonies in South America. Many indigo plantations were established by European powers in tropical climates; it was a major crop in Haiti and Jamaica, with much or all of the labor performed by enslaved Africans and African Americans.