In chapter nineteen of Guns, Germs, and Steel, Jared Diamond refers to Madagascar as "the biggest anomaly."
Geographically, Madagascar is closer to Africa than any other continent (it is only two hundred and fifty miles away) and separated from Asia and Australia by the "whole expanse of the Indian Ocean." Despite that, the people of Madagascar are a mix of two influences. One is African blacks, and that is not surprising. What is surprising is that the other is clearly recognizable as being descended from Southeast Asia. Even more astonishing is that all of the people of Madagascar speak a language spoken only on Borneo, an island which is located four thousand miles away.
There is no evidence of any other such influence anywhere near Madagascar, and Diamond sees this as "the single most astonishing fact of human geography for the entire world." He cannot fathom how a primitive people, such as the people of Borneo, could have established themselves in Madagascar before the Europeans arrived in 1500--"presumably voyaging in boats without maps or compasses."