Amid environmental devastation, an often-hostile police force and army, modern slavery by a hostile ethnic majority and decades of persistent civil war, Pygmy communities in the Congo have found one source of subsistence: Growing cannabis for sale.

National Geographic has a long read on the Pygmy communities that grow and sell marijuana, a move that can dramatically increase their income in one of the poorest countries in the world. Cannabis is still illegal in the Democratic Republic of the Congo, though the enforcement of that law varies: According to NatGeo, some police and soldiers will sometimes beat arrest the Pygmies for growing marijuana — while other soldiers and police are some of their best customers.

The potential payoff for growing marijuana is big: In a nation where the average income is $2 a day, and where the 27,000 Pygmies who live in the North Kivu region survive on less than a dollar a day, marijuana can bring in some 50 cents per plant — between $8 and $100 a week.

The Pygmy people harvest wild marijuana in Virunga, Africa’s oldest national park. Their people were evicted from their homes when the park was created in the 1950s, but they continue to hunt and gather there, even though it’s against the law. (National Geographic reports that some 20 million indigenous people worldwide have been displaced by conservation efforts.)

Still, heavily armed rangers patrol the park, attempting to prevent the Pygmies from gather honey, potatoes and marijuana, among other items. Though Virunga is held up as a conservation success story, there has been no easy reconciliation of the conservation movement’s goals with the difficulties suffered by the indigenous people displaced from its lands. According to Survival International, an indigenous advocacy group, the anti-poaching squads subject the Pygmies to harassment, arrests, violence and even death.

The Pygmies sell the plants for a profit, and use the leftovers for medicinal purposes, with different parts of the plant to treat stomachaches and lost appetites, coughs, parasites, flue and fever. A 2015 study found that cannabis use among the Pygmy population in the Central African Republic decreased parasitic loads in the bodies of research subjects.

For the full story, photos and videos, go to NationalGeographic.com.