The Paraguayan harp deserves special mention as a popular instrument with a national style associated with it. The harp in South America dates back to at least 1556–1557, possibly as early as the beginning of the 16th century. It was introduced to Paraguay by Jesuit priests who came to evangelise (the native population of indigenous Guaranis) and founded many missions, called "reducciones" . It was frequently used in church music in place of the organ or harpsichord. The Paraguayan harp is the national instrument of Paraguay, its shape and size were consolidated in the early 20th century by interpreter and composer Felix Perez Cardozo, who composed some of the most memorable pieces for the Paraguayan harp. It stands about 1.5 metres (5 ft) high and is very light and portable. The sound box is made of cedro (a type of mahogany) and pine. It is played either in a sitting position, or standing up when it is fitted with extending legs. The harp has 36 or 37 strings, which go through the centre of the neck making it identical from either side, this being a unique characteristic of the Paraguayan harp. The lower strings were once made from the leather of the belly of horses and the upper strings of steel but now they are all made of nylon. The original wooden pegs have mostly been replaced by mechanical pegs like those on the guitar, making them easier to tune.