“Market guards or police officials would ask me to follow them to an empty room outside the market, or some other place they’d pick,” said a former trader in her 40s. “They consider us toys. We are at the mercy of men.”

“Sometimes,” she said of the psychological torment from such abuse, “out of nowhere, you cry at night and don’t know why.”

The women interviewed by Human Rights Watch said they seldom reported the crimes for fear of reprisal, and because of widespread stigma attached to rape victims. The coerced sex has become so common that the men don’t think their actions are wrong, and the women have come to accept such behavior, some said.

“Corruption is so rampant that anybody without power has no choice,” said the husband of the trader in her 40s. “Traders like my wife have to accept that sexual coercion is part of social and market dynamics. It is the only way to survive.”

“I know what I know,” he said. “But we don’t talk about it.”

Also vulnerable are women who enter China illegally to find work or smuggle goods. When they are caught and repatriated, they are exposed to widespread sexual and other abuse in holding centers and prisons, according to Human Rights Watch, whose report echoed earlier findings on that issue.

In a 2014 survey of 1,125 North Korean defectors by the South’s Korea Institute for National Unification, nearly 38 percent said that sexual harassment and rape were “common” in those facilities. Thirty-three of the defectors said they had been raped there.

“Every night, some woman would be forced to leave with a guard and be raped,” a former trader in her 30s who was detained in a holding center told Human Rights Watch. “Click, click, click was the most horrible sound I ever heard. It was the sound of the key of the cell of our prison room opening.”