How did the Sakalava empire gain control over much of western Madagascar?

The Sakalava empire gained control over much of western Madagascar through the political and military influence of the Maroserana dynasty, which established the states of Menabé and Boina in the 17th century.1

The empire’s expansion and consolidation were driven by several key factors:

• Military and Social Integration: The original Sakalava warriors intermarried and merged with hundreds of west-coast clans, extending "Sakalava citizenship" to these groups to build a unified identity.1
• Religious Unity: The Maroserana royals were elevated to the status of sacred ancestors upon their deaths, providing a unifying religious bond for all Sakalava people.1
• Economic Power: The empire leveraged its control over the region to engage in a lucrative trade of cattle and slaves with Europeans, exchanging these for guns and manufactured goods, which further bolstered their military dominance.2

At its height in the 18th century, the Sakalava empire extended its rule over nearly half of the island before internal power struggles and the rise of the Merina kingdom led to its eventual decline.21