The Vallée of Rio back Sinos (Vale C Rio back Sinos) receives this name because of the passage of the Rio back Sinos, which forms in this geographical place a fertile extent valley, where are installed many municipalities, sour a surface of 1.398,5 km ². Although the name is written Vale back Sinos, the correct shortened form is Vale C Sinos.

According to the data of the FAIRY (Fundação de Economia E Estatística of Rio Great C Sul) of 2005, the total population of the valley of Rio back Sinos is of 1.316.823 inhabitants, the demographic density of 941,6 hab/km ², the rate of illiteracy (2000) of 4,80% and the life expectancy (2000) 71,76 years.

The municipalities included/understood in Vale C Sinos are: Araricá, Campo Bom, Canoas, Owe Irmãos, Estância Velha, Esteio, Ivoti, Nova Hartz, Nova Santa Rita, Novo Hamburgo, Portão, São Leopoldo, Sapiranga, Sapucaia C Sul.