There are lots of Brazilian-born persons living in Uruguay, for a number of reasons. Above all, the frontier, which is one of the most permeable in the world; the neighboring cities of Rivera and Santana do Livramento, as a matter of fact, function closely as if they were a single big city. Then the languages spoken in both countries are mutually intelligible, with a hybrid variant, the Riverense Portuñol language. Historical reasons are also important: when the Southern Cone was disputed between the Spanish and Portuguese empires, a good portion of the territory of modern Uruguay changed hands several times. And, shortly before Uruguay was born as an independent nation, it was annexed to Brazil with the name of Cisplatine Province. Last, but not least, slavery was early abolished in Uruguay but persisted in Brazil for decades to come, so many Afro-Brazilian slaves escaped to Uruguay.