In the bare dirt courtyard of a low-slung building in a small farming village, a group of girls chase one another in a round of kabaddi, a local schoolyard game a bit like Red Rover. It could be any small village school in a desperately poor rural area of India — except that these girls have barely escaped a 21st century system of slavery. More children are sold into prostitution in India than in any other country. In villages such as Simraha, it is not uncommon for girls as young as 12 or 13 to be sold. At this school, many of the children playing games, doing homework, helping with dinner and making crafts are the daughters of prostitutes. They are members of a marginalized caste known as the Nat community, which is trapped in a system of hereditary prostitution. Their school, not far from the border with Nepal in the Indian state of Bihar, is part of a national program of girls’ boarding schools called Kasturba, Gandhi, Balika, Vidyalaya, intended specifically for minority groups. Founded by the non-profit organization Apne Aap, its supporters and the Bihar stategovernment, the school aims to break the bonds of caste and inequality. “The school keeps them safe and away from the home-based brothels that they were growing up in,” said Ruchira Gupta, Apne Aap's founder. “Otherwise, they would join their mothers in prostitution.” The Nat group has been relegated to the margins of Indian society since the 1870s, when it was classified as a “criminal tribe” by British colonial rulers. Gupta's group works to get the girls out of the reach of men who might sell them — by enrolling them in the boarding school but allowing weekend visits with their mothers and siblings. “It's not a five-star school,” Gupta said. “But it's neat and clean.” For most of the 100 girls at the school, it's the first time any member of their family has been offered access to education. A few graduates of the school are even heading off to college — with ambitions of becoming lawyers and doctors. But many struggle to achieve a much smaller ambition: avoiding being caught up in systemic prostitution. At the school, fathers regularly put pressure on the girls to do their “family duty” and start working as prostitutes. Some fathers have tried to snatch the girls back.by keeping costs down, Apne Aap is able to keep the girls in school for about $160 a month per student. But keeping them safe is a long-term commitment, Gupta said. “Many people think: ‘Oh, enroll a child in school,’” Gupta said. “But keeping that child in school is even harder.”