How large was the Betsimisaraka confederation at its height?

The Betsimisaraka confederation, founded in the early 18th century by Ratsimilaho, was a significant political entity along the eastern coast of Madagascar.12

Historical accounts regarding the size of the confederation at its height vary:
* One source notes that the confederation united various chiefdoms along a 400-mile (650-kilometre) stretch of the coast.1
* Another source describes the confederation as extending along more than 200 miles of coastline.2

The confederation, whose name means "Inseparable Multitude," was a successful attempt to unite the coastal peoples of the eastern littoral. Following the death of Ratsimilaho in 1750, the confederation began a period of disintegration, eventually collapsing in 1791.12