 In the mid-16th century these royal Merina villages ("rova"s)—now fortified with stone walls, gateways and deep defensive trenches—were united under the rule of King Andriamanelo (1540–1575), who initiated the first military campaigns to expel or assimilate the Vazimba population by force.Villages inhabited by the "andriana" (noble) class established by Andriamanelo typically contained a "rova" or palace compound.The rova's earliest defining features had crystallised among the Merina as residences for local rulers at least 100 years before the emergence of the united Kingdom of Imerina under Andriamanelo.