Betsileo is the generic denomination of the populations occupying the southern part of the central grounds of Madagascar.

The traditional territory betsileo extended since the Mania river in north to the foot from the solid mass from Andringitra in the south. Towards the west, this one is limited by the chain of Bongolava and towards the east by the Eastern forest occupied by the Tanala. The name even of Betsileo (“the many invincible ones”) seems to be inherited that carried initially by the Merina of the kingdom of Andrantsay and was applied only tardily to their neighbors of the south, after Andrantsay was found reinstated in the remainder of the Imerina. That would be explained by the fact why at the time of its formation under Andrianampoinimerina and Radama 1st, the province of the Vakinankaratra was also used to extend the authority merina on the lately conquered worldwide of the futures Betsileo which, up to that point, do not appear to have had themselves a common noun.

With the Sihanaka of the north-eastern part of the highlands, Betsileo are those whose language and traditional civilization have the most affinity with those of Merina. On all the other plans however, the differences carry it and since always, the members of the two groups hold with well marking their respective identity.

Before the conquest merina, the forever known country betsileo of political unit, even if the traditions report that the sovereigns of the various kingdoms which were going to develop to with it came at the beginning from the kings of the Manandriana, the kingdom of north occupying the current area of Ambositra. This kingdom of Manandriana would have been made up about the 16th century and had for first large Andriantara sovereign the Ist other kingdoms which appeared thereafter are:

1. the Isandra in the south-west which reached its apogee in second half of the 18th century under Andriamanalina 1st;
2. the Lalangina in the south-east (area of current the Fianarantsoa), rested by king Rahasamanarivo;
3. the Arindrano in the south (current area of Ambalavao) which then was divided itself into two to give rise to the southernmost kingdom of the Vohibato.

Their history shows that during the last centuries, the populations betsileo were in constant expansion, initially towards the south and the west and then towards north in country merina where they represent important minorities nowadays.

From the end of the 19th century, Betsileo convert massively with the Catholicisme, a religion which ended up becoming an important component of their modern identity.