Francis, the first pope from the Americas, has long spoken out on behalf of indigenous peoples and the environment.
The church has scheduled a Synod of Amazonian bishops for next year at the Vatican, underscoring the pontiff's concern for the area.
In advance of the pope's visit, a carnival-like atmosphere overtook Puerto Maldonado on Thursday.
Various indigenous bands and performing groups made their way through the city streets, playing music, dancing and hoisting aloft likenesses of the Virgin Mary and Jesus Christ. Some celebrants donned masks and colorful costumes. The celebrations continued after midnight.
On the streets near the central square, hawkers sold all stripes of pope paraphernalia -- T-shirts, medals, banners, flags and other objects, all featuring the image of Papa Francisco. The merchants appeared to be doing a brisk business.
Authorities in Puerto Maldonado have banned most vehicular traffic on Friday, to coincide with the papal visit. That will ground the town's most popular conveyances -- motorbikes and motorcycle rickshaws, which usually clog the streets. Thousands of extra police officers have been deployed.
Francis is to arrive here after a four-day swing through Chile, Peru's southern neighbor, that saw him address many themes -- the pope denounced clerical sexual abuse; he praised indigenous culture; he extolled the role of immigrants and called for peace in Chile's central Araucania region, where tensions have mounted between indigenous Mapuche people and other residents.
The pope is scheduled to return to Lima Friday afternoon, and then head north on Saturday to celebrate Mass in the Peruvian city of Trujillo. He is to conclude his week-long trip on Sunday in Lima with a recitation of the Angelus prayer in the central Plaza de Armas and a Mass at an air base.
(Special correspondents Adriana Leon in Lima and Liliana Nieto del Rio in Puerto Maldonado contributed to this article.)
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