Editors’ Note Appended

In remote western Nepal, where the Himalayas brush the sky, girls spend their childhoods as they have for generations, dreading growing up.

Puberty starts a monthly exile. An entrenched, superstitious practice linked to Hinduism, Chaupadi, considers menstruating women impure and bad luck, rendering them untouchables. Menstruating women are banished, often to forests where they sleep in crude, cubbylike sheds or caves, braving extreme weather and lurking predators, from snakes to rapists. There they stay as long as their periods last, several days a month, and they must do this for 35 to 40 years.

Rarely — usually only when death strikes — does this practice, outlawed by Nepal’s Supreme Court in 2005, make the news. Last month, a 15-year-old girl choked to death on smoke after lighting a fire in her menstrual hut to keep warm, just weeks after a 21-year-old woman died the same way. Their deaths generated headlines for perhaps a day.

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Poulomi Basu, a documentary photographer and journalist, wants to expose Chaupadi in ways that last beyond a news cycle. She has trekked for days in dense wilderness where the practice occurs to find women in exile, learn their stories and spread them far and wide.

Ms. Basu spent three years, from 2013 to 2016, documenting women during their monthly confinement, to reveal the dangers and hardships Chaupadi creates in poor farming villages. The portraits, landscapes and details in her Nepal portfolio, “A Ritual of Exile,” offer a narrative of Chaupadi that leaves the viewer both stunned and engaged by the women’s plight.

“A Ritual of Exile” shows the jarring reality of women boxed into tiny holes amid wild, lush nature, a landscape usually associated with beauty, freedom and adventure. The portraits bare the sorrow the women endure, usually in silence. Raised to accept their condition without complaint, the women have told Ms. Basu of travails that repeat themselves year after year. She has documented stories of women and girls abducted and raped; bitten by snakes; mauled by jackals; starved for days; prostrated by heat; burned by warming fires. They have told her of cases of kidnapping and murder.

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In addition to meeting menstruating women, Ms. Basu has encountered women in confinement just after childbirth — also considered impure — in huts with their babies. She has witnessed a young girl beaten by a healer after seeking help for fever and pain during her period. (The girl’s presence, Ms. Basu was told, might make her house catch fire, attract hungry tigers to the livestock or sicken anyone nearby.) Ms. Basu has watched women scramble for dry rice thrown at them from afar. She has met women forced into prison-style hard labor, such as breaking rocks for use in roads or chopping and hauling firewood for long distances through harsh terrain.

Chaupadi, while extreme, rang a bit familiar to Ms. Basu, who grew up Hindu in Calcutta, India. After puberty, she was prohibited from attending religious festivals or entering the kitchen while menstruating. Nor was she allowed to pursue creative passions or see the world. Not until her father died, when she was 17, could she leave her limited, working-class environment and pursue life’s possibilities.

Eventually, after teaching herself photography using her father’s old Nikon FM2, Ms. Basu earned a master’s degree in art at the London College of Communication. In 2012, she was awarded the Magnum Foundation Human Rights scholarship at the New York University Tisch School of the Arts. The honor validated her love of photography and her passion for social justice.

“A Ritual of Exile,” which she finished with help from the Magnum Emergency Fund Award and the Prince Claus Fund, was a finalist for the W. Eugene Smith Fund for Humanistic Photography in 2016. Ms. Basu, 33, calls it the first chapter of a project that will span several cultures.

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“I want to bring home the idea of how women are silenced and made subservient all around the world using religion, traditions and customs,” she said.

Early images in “A Ritual of Exile” were used by WaterAid, an international nonprofit that helps establish sustainable water supplies and work toward safe hygiene practices in developing countries, in its “To Be a Girl” campaign. (The images helped raise money for improved menstrual hygiene conditions for women in Nepal and India.) Ms. Basu has discussed the project on radio shows and has displayed it in several festivals and photography exhibitions. Eventually, she hopes “A Ritual” will reach young people who can help change the world.

“Ideally, I’d like to collaborate with an academic and create a school textbook where you’re not just talking about gendered violence, but you actually see what these issues look like,” she said. “We’ve grown up in a man’s world, fighting and suffering, and I want young women to read that. I want it to be part of our history.”

Editors’ Note (April 17, 2017)

After publication of this article, questions were raised about the circumstances under which several photographs were taken. Because of incorrect information provided by the photographer, a portrait of Saraswati, a 16-year-old mother of a newborn, was accompanied by an inaccurate caption. The caption asserted that Saraswati was “forced to stay in a closed dark room” with her child, that “she was not allowed to clean herself” and that she “was forced to cook” in the room while her newborn “coughed from the smoke.” Actually, mother and child left the room — where the door was often open — when her husband cooked meals, and waited outside until the smoke cleared. Moreover, Saraswati also went outside twice a day, including in the morning to wash herself.

Another image, of Saraswati being taken to a hospital on a stretcher, did not mention that the photographer and an associate paid for the stretcher. Had editors known this, the image would not have been used.

Both images have been removed from the slide show.

Follow @poulomibasu and @nytimesphoto on Twitter. Poulomi Basu is also on Instagram. You can also find Lens on Facebook and Instagram.