MEXICO CITY - Pope Francis traveled to Mexico's southern border and celebrated mass with the country's indigenous people.

For many migrants from Central America, Mexico's southern border region is the start of a dangerous journey north, reports CBS News' Adriana Diaz.

Before an audience of thousands, Pope Francis presided over mass in Chiapas, the center of Indian culture in Mexico.

Get Breaking News Delivered to Your Inbox

Speaking in three indigenous languages, he chastised Mexico's elite in his homily, saying that the indigenous population has been systematically excluded from society.

The crowd started forming overnight in Chiapas, where Mexico meets Guatemala.

The southern border is also where hundreds of thousands from Central America enter Mexico on a dangerous journey to the U.S.

They try to hitch a ride atop Mexico's north-bound freight train, known as "the Beast."

At the halfway point, the trains come through Mexico City on their way north.

Along the way CBS News spoke to a migrant who left Guatemala for better opportunities. He's been traveling for a month and he asked CBS News not to show his face or use his name. He said he's traveling so he can send money back to his wife and four kids, and to be able to afford university for his oldest, who's 17.

"People die on the train," he said, adding they can lose limbs and he's even seen whole families fall off the train.

He said he lived in Houston, Texas, for 7 years before he was deported.

"We've dealt with trouble, hunger, and violence," the migrant said. "We've been assaulted but we're making it because we're also being helped by people in Mexico. There are good people here. There are both good and bad people, but we do it for our families."

He praised Pope Francis' concern for migrants, adding he hopes to be at the U.S. border when the pope is there

"We want to support him when he's speaking about the border and migration," the migrant said.

The pope's itinerary itself reflects the migrants path.

Today he's on the southern border, and ends his trip on the northern border with the U.S.