Complex sentence: Andrianampoinimerina's son, Radama I, succeeded in uniting nearly the entire island under his rule, and established the Kingdom of Madagascar; a line of Merina monarchs then governed the island until its colonization by the French in 1896.
Split into simpler sentences: Andrianampoinimerina's son, Radama I, succeeded in uniting nearly the entire island under his rule, and established the Kingdom of Madagascar. A line of Merina monarchs would continue to govern the island until its colonization by the French in 1896.