The microregions have a huge integration with cities. Actually, Ourinhos is the most populated city in region, followed by Assis, Paraguaçu Paulista and Santa Cruz do Rio Pardo, they have populations of more than 40,000. The limits of the region with Paraná state is Paranapanema River. The region was unoccupied until the twentieth century, when the first villages were created, but only with arrival of the railroad (Estrada de Ferro Sorocabana, Sorocabana Railway) the region
