The 19th-century unification of Madagascar under the Merina monarchy (culminating ~1824–1895) was transformative across five dimensions:
Ended centuries of fragmented kingdoms (Betsileo, Sakalava, Bara, Antaimoro, etc.) and endemic warfare. Enabled uniform laws, taxation, administration, and defense — prerequisites for modernization.
Merina rulers promoted assimilation policies: common language (Malagasy standardized), shared institutions, royal rituals. Created "Malagasy" identity transcending 18+ ethnic groups — critical for post-colonial nationhood.
Monarchs (especially Radama I, Ranavalona I, II, III) patronized hira gasy (musical theater), kabary (oratory), valiha (tube zither), lamba (textile), oral literature. Unified court culture preserved traditions French colonialism later threatened.
Unification was Merina-led, sometimes coercive — creating ethnic tensions persisting today. But the state framework it built survived colonialism and remains Madagascar's political skeleton.