Local private banks introduced the first banknotes in Peru around 1864. These Peruvian banknotes (issued between 1864 and 1922) used currency names like Soles, Pesos, Incas and Libras. There was no unified monetary system for the country until 1926, when the Central Reserve Bank of Peru (Banco Central de Reserva del Peru) started issuing paper money.
Peru had since 1897 five main monetary systems. The first one was the Libra Peruana de Oro (Peruvian Gold Pound) that was in circulation as legal tender from 1897. In 1930 followed a new currency called the Sol de Oro (Golden Sun). Because of high inflation, the currency of the era of Republican Peru was abandoned in 1985 and the Inti introduced. The bad economic state of Peru and terrorism in the late 1980s, the Inti lost its value quickly. Hyperinflation struck the country, and the Peruvian government was forced to introduce a new currency in 1991: the Nuevo Sol (New Sun). They introduced the Nuevo Sol at a rate of 1 Nuevo Sol = 1,000,000 Intis. The return to this name was considered appropriate as it could be derived from historical use and divination of the sun as a symbol of power and as a way of connecting the new currency to the old Inti, which was named after Inti, the Sun God of the Incas. On the 15th of December 2015, they changed the name of the Peruvian currency to "Sol" (Sun).
Today you can still buy old Libras, Intis and Sol bills, especially in the small shops behind the main post office in Limas City Center. These bills aren't fake, but keep in mind that they are not legal tender. You can't exchange them or buy anything with them, even if you are told otherwise!