“I would have been happy to let her grow up with us,” she said.

The family’s case is a kind of dark distortion of the Afghan tradition of the groom’s family paying a “bride price” to the family of the wife-to-be. The practice is common particularly in Pashtun areas, but it exists among other ethnic groups as well and can involve thousands of dollars. In this case, the boy who is receiving Naghma as a wife, instead of paying for her, will get her in exchange for the debt’s forgiveness.

Because Naghma, whose name means melody, was not chosen by the groom, she will most likely be treated more like a family servant than a spouse — and at worst as a captive slave. Her presence may help the groom attract a more desirable second wife because the family, although poor, will have someone working for it, insulating the chosen wife from some of the hardest tasks.

Anthropologists say this kind of use of women as property intensified after the fall of the Taliban, said Deniz Kandiyoti, a professor at the School of Oriental and African Studies at the University of London.

The most recent anthropological studies of the phenomenon were of indebted drug traffickers who sold their daughters or sisters to settle debts, she said. These are essentially distress sales. And unlike the norm for marriage exchanges before the past three decades of war, the women in some cases have become salable property — stripped of the traditional forms of status and respect, she said.

Regrets

Almost from the moment he agreed to the deal, Mr. Mohammad began to regret it and think about all that could go wrong. “If, God forbid, they mistreat my daughter, then I would have to kill someone in their family,” he said as he stood at the edge of the camp in a muddy lot in the cold winter dusk.

“You know she is very little, we call her ‘Peshaka,’ ” he said, using the Pashto word for kitten. “She is a very lovely girl. Everybody in our family loves her, and even if she fights with her older brothers, we don’t say anything, we give her all possible happiness.”

He added: “I believe that when she goes to that house, she will die soon. She will not receive all the love she receives from us, and I am afraid she will lose her life. A 6-year-old girl doesn’t know about having a mother-in-law, a father-in-law, or having a husband or being a wife,” he said.