SAN CRISTOBAL DE LAS CASAS, Mexico (AP) — Pope Francis denounced the centuries-old exploitation and social exclusion of Mexico's Indians on Monday, saying the world should instead ask their forgiveness and learn from their culture and appreciation of nature.

Francis celebrated the Indians during a visit to the southern state of Chiapas, a center of indigenous culture. He presided over a Mass in three native languages in a service that also featured a traditional dance of prayer and a celebration of married deacons in Chiapas, whose role has been revived under his papacy.

In his homily, history's first Latin American pope melded two of his core concerns: appreciation for indigenous cultures and the need to care for the environment.

"We can no longer remain silent before one of the greatest environmental crises in world history," he told the crowd of several thousand indigenous people, some in traditional dress, who gathered under clear blue skies at a sports complex in the mountain city of San Cristobal de las Casas.

"In this regard, you have much to teach us."

The soft sounds of marimbas accompanied the Mass, which was celebrated in front of a replica of the brilliant yellow and red facade of the San Cristobal cathedral, where Francis visited later in the day.

Crowds chanted "Long live the pope of the poor!" and "Welcome, pope of the struggle!" as he arrived. Some 500,000 faithful were expected to see the pope in the city, including about 100,000 who gathered on the dirt field for the Mass.

Francis issued a sweeping apology last year for the Catholic Church's colonial-era crimes against America's indigenous. He revisited the issue again Monday, denouncing how, "in a systematic and organized way," indigenous people have been misunderstood and excluded from society over the course of history.

"Some have considered your values, culture and traditions to be inferior," he said. "Others, intoxicated by power, money and market trends, have stolen your lands or contaminated them."

He called for a collective "Forgive me."

"Today's world, ravaged as it is by a throwaway culture, needs you!"

The pope has frequently expressed admiration for indigenous peoples, particularly their sense of being custodians of the environment. As archbishop in Argentina, he was heavily responsible for a major document of the entire Latin American church hierarchy in which bishops praised the harmonious way indigenous people live with nature. As pope, he penned an environmental encyclical denouncing the exploitation of the planet by the rich at the expense of the poor.

Indigenous communities have legal rights to much of Mexico's forest and desert lands, and have long battled with outsiders to protect them — and to share in the revenues they produce. Mining and commercial logging interests that were granted concessions by national or state governments long denuded or polluted indigenous lands.

Francis' visit to Chiapas and celebration of native culture is in many ways a swipe at the Mexican church hierarchy, which has long sought to downplay the local culture and bristled at the "Indian church," a mixture of Catholicism and indigenous culture that includes pine boughs, eggs and references to "God the Father and Mother."

It was a tradition that was embraced by the late bishop of San Cristobal de las Casas, Samuel Ruiz, who ran afoul of both the Mexican church and the Vatican at times for his support for indigenous culture. While Ruiz is still a controversial figure, Francis' decision to come to San Cristobal, celebrate the Indians and use the local languages and customs in Mass was a strong sign that he was on Ruiz's side.

Shortly after midnight, worshippers began filing into the site of the Mass, which included readings, prayers and hymns in the three main indigenous languages of Chiapas: Tzeltal, Tzotzil and Chol, which are spoken by just over 1 million people, according to Mexico's latest census.

The pope presented an official decree authorizing at least one of the languages to be used, some 50 years after the Second Vatican Council paved the way for Mass to be celebrated in the vernacular rather than in Latin.

His predecessor, John Paul II, also dabbled with comments in Indian languages during a 1990 visit to Chiapas, though less formally.

Despite the pope's overture, residents of Chiapas said they believe Francis is coming mostly to confirm their faith, not their status as indigenous.

"It doesn't matter that I'm indigenous; I think it's more that I'm Catholic," said Emanuel Gomez, a 22-year-old Tzotzil man. "The pope comes to encourage our hearts and faith as Catholics."

He added, though, that the visit would "lift us up so we don't feel scorned by the powerful and rich."

According to government statistics, about 46 percent of Mexicans were living in poverty in 2014. That number surges in Chiapas, where some 76 percent were poor and 32 percent in extreme poverty, the highest for any Mexican state.

Francis has insisted that his is a "poor church, for the poor." After the Mass, Francis was scheduled to hear testimony from Chiapas families about the hardships they face.

"He comes to redeem an entire struggle by the people," said the Rev. Marcelino Perez, an indigenous priest who was charged with translating the homily into Tzotzil.

San Cristobal is home to two of the most famed religious defenders of indigenous people in Mexican history: Bishops Bartolome de las Casas in the 16th century and Ruiz, who died in 2011.

Both were beloved by indigenous people and widely reviled among the wealthy classes and much of the church hierarchy. Many officials accused Ruiz of acting on behalf of Zapatista rebels in their 1994 uprising for greater indigenous rights.

Part of the liberation theology movement that swept Latin America after Vatican II, Ruiz tried to fend off the rapid growth of Protestant denominations by adapting to indigenous customs.

One of his measures was to rely heavily on married male lay workers because local culture granted more respect to men with children than to childless, celibate men such as priests. Some in the church worried the married deacons were taking on priestly functions.

In 2002, under Pope John Paul II, the Vatican asked the Chiapas diocese to halt deacon ordinations. But under Francis, the ordinations were renewed in 2014.

In a sign that Ruiz remains a controversial figure, the Vatican declined to say whether Francis would pray at his tomb during his visit to the cathedral.