Complex sentence: The Paraná and Paraguay rivers separate the Chaco province from Corrientes Province and the Republic of Paraguay while to the north the river Bermejo forms another natural border, dividing Chaco Province from Formosa Province.
Split into simpler sentences: The Paraná and Paraguay rivers separate Chaco province from Corrientes Province and the Republic of Paraguay. To the north, the river Bermejo forms another natural border, dividing Chaco Province from Formosa Province.