Pope Francis has travelled to Chiapas state, centre of Mexico's poor, indigenous south, to preside over a mass in native languages thanks to a new Vatican decree approving their use in liturgy. It will include readings, prayers and hymns in the three main indigenous languages of Chiapas: Tzeltal, Tzotzil and Chol, which are spoken by just over a million people, according to Mexico's latest census.

Before dawn, people began gathering along the road outside a sports stadium in San Cristobal where the pope will celebrate mass, many in indigenous dress.

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Mayan Tzotzil natives queue outside the place where Pope Francis is to celebrate an open-air mass in San Cristobal de Las Casas, Chiapas stateMoyses Zuaiga/AFP
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People wearing indigenous clothes wait for Pope Francis to celebrate mass in San Cristobal de las CasasEdgard Garrido/Reuters
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Indigenous people wait for Pope Francis to arrive to celebrate mass in San Cristobal de Las Casas, Chiapas StateEdgard Garrido/Reuters
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People wait for Pope Francis to arrive to celebrate mass in San Cristobal de Las CasasEdgard Garrido/Reuters
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Catholic faithful await for the arrival of Pope Francis in San Cristobal de las CasasRonaldo Schemidt/AFP
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A group of indigenous teens smile as Pope Francis arrives at the Tuxtla Gutierrez airportGabriel Bouys/AFP
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Pope Francis is welcomed at the Tuxtla Gutierrez airport before heading to San Cristobal de Las Casas to celebrate mass with representatives of the indigenous communitiesGabriel Bouys/AFP
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People wearing traditional indigenous Mexican clothing head to the venue of the Pope's open-air mass in San Cristobal de las CasasRonaldo Schemidt/AFP
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Indigenous women wait for the arrival of Pope Francis in San Cristobal de las CasasRonaldo Schemidt/AFP

Francis is expected to highlight the struggle of Central American migrants during his visit. Thousands of people from neighbouring El Salvador and Guatemala are believed to have crossed over the porous border of rivers and jungle in Chiapas for a chance to see the Pope.

Francis's visit comes amid strong challenges to the church in the southern state, including huge inroads by evangelical Protestants who have helped turn Chiapas into the least Catholic area in Mexico. According to the 2010 census, Chiapas was 58% Catholic, compared to a national average of 83%.

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Salvadoreans queue for the open-air mass in San Cristobal de Las Casas, southern MexicoMoyses Zuaiga/AFP
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Catholic faithful queue outside the venue of Pope Francis's open-air mass in San Cristobal de Las CasasMoyses Zuaiga/AFP
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In the early morning fog, people wait for Pope Francis to celebrate mass in San Cristobal de las CasasEdgard Garrido/Reuters
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Nuns wait for Pope Francis to arrive in Tuxtral GutierrezCarlos Jasso/Reuters
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A girl peeks from behind public telephone booths with photographs of Pope Francis in Tuxtla Gutierrez, Chiapas StateCarlos Jasso/Reuters

The Pope last year apologised for the role of the church in the conquest of Latin America. Francis is visiting some of the most-marginalised parts of Mexico. On Sunday, he took a swipe at the its rich and corrupt elite in a mass near the slums of Ecatepec, one of the country's most-violent cities.