As early as possible, have an Islamic country either legally ban slavery or de facto abandon the practice of it.
Is this realistic in the pre-modern age? What effects would it have? (although I suspect the conditions required for an Islamic economy to eliminate slavery would be more butterfly-inducing than elimination itself)
Is this realistic in the pre-modern age? What effects would it have? (although I suspect the conditions required for an Islamic economy to eliminate slavery would be more butterfly-inducing than elimination itself)