Every year, busloads of young musicians armed with violin cases travel on dirt roads across the Bolivian jungle to bring their baroque music to this lush tropical region.

With 10 touring orchestras and hundreds of children, some as young as eight, they play over five evenings in the churches of 10 local towns as part of Chiquitanía's annual baroque music festival.

They play in buildings like the 18th-century Jesuit church in San Xavier, which, with its massive white facade, original terracotta-coloured murals and carved wooden colonnades, dominates the cobblestone town square.

Outside, the singing of cicadas drowns out any human noises. But inside, a choir is singing Domenico Zipoli's Mass in F Major.

"Baroque music comes natural to me," says one of the singers, 13-year-old Mary Eliza. "It's very special. It makes me feel at peace and at ease with myself."

Consuelo Castelló, who is in charge of the music school in San Xavier, says the children here were "born with music in their blood".

Jesuit missionaries spent almost 80 years converting the indigenous population to Christianity, until their expulsion in 1767. They built missions in the Bolivian jungle which still maintain and preserve the Jesuit musical legacy. More than two centuries later, the missions in Bolivia have so well preserved the Jesuit cultural and artistic living legacy that in 1990 six of these missions were declared worthy of protection by Unesco.

Castello says that music is a critical part of this life culture. "It's a horrible punishment to tell the children that, because they may have missed school one day, they won't be allowed to play," she says.

The festival in San Xavier was opened with Domenico Zipoli's Mass, followed by two sonatas for chamber orchestra, the anonymous pages of which, along with thousands more examples of indigenous baroque music, were discovered and restored in the 1970s.

One of the organisers of the festival, Yaneth Mallea, believes it is because of this recovered musical repertoire that the children feel great pride in being part of an orchestra or choir.

"Some have played for kings [in Europe] and in music halls in the US," she says. "And knowing that a Chiquitano from a far corner of Bolivia goes to play in Europe brings a lot of happiness to them and their indigenous family."

Preserving this living culture is however sometimes a challenge for these isolated and poor communities. Musical instruments can be in short supply; photocopying sheet music is costly; and not many children have the means to carry on playing professionally in the big cities.

Despite the difficulties, the Chiquitanos are determined to keep their musical heritage alive. They may often be playing notes written by anonymous composers from the past, but they feel this is their music.