For thousands of North Korean women, the decision to flee their impoverished, repressive homeland often puts them at the mercy of human traffickers. In China, many are forced into prostitution or marriage with Chinese men.
Bang Mi Sun left North Korea and crossed illegally into China in 2002. Countless other North Korean women have done the same since the mid 1990s. Hunger and severe shortages of necessities such as medicine and heating fuel have driven them from home.
She says after she and her two children crossed the Tumen River, a Chinese family welcomed them. The son said Bang should earn money to feed her children. She says she thought he was offering her a job.
But instead of a job, the Chinese family arranged for human traffickers to separate Bang from her children and sell her into marriage to a Chinese farmer.
She says her Chinese husband was 15 years older, and had a crippled leg. From that point on, she says, she was his slave. If she did not obey his orders, he beat her, and often locked her in a storage shed for the full day.
Eventually, she made it to South Korea, but human rights activists say Bang's story is typical of tens of thousands of other North Korean women who flee poverty and repression at home.
Mike Kim is the founder of Crossing Borders, an organization that helps North Korean refugees. He says traffickers prey on North Korean women systematically.
"Women venture into China on their own and they're abducted, or Chinese businessmen will go into North Korea in conjunction with North Korean businessmen and make a pitch," Kim said. "You know, 'we've got an excellent job for your daughter in a nearby village across the border, she's going to make X salary, she's going to be able to send money back to support.' Of course they enthusiastically agree, and once they cross into China, they're sold." he continued.
Kim spent four years doing humanitarian work along the China-North Korea border. He says many women face what amounts to a slave trade.
"It's like a market setting. They'll line up women, have them adjust their age, they'll pretty them up with makeup, put on nice clothes, and people begin bargaining. And the highest bidder wins. Women are raped by their traffickers, and then raped by the men that they're sold to. They're tied down to chairs, to beds - until their wills are completely broken," said Kim.
Lee Hae-young is a human rights researcher in Seoul and co-founder of an aid group called BASPIA - the Blanket and Sponge Project in Asia. Her two years of interviews with North Korean women in China are the basis of a new report, "Lives for Sale."
She points out that China is an ally of North Korea, and does not recognize North Korean border-crossers as refugees. When women arrive in China, they know they can be turned in to police and returned home at any time - to face harsh punishment.
"They really have no other option but to rely on anyone they encounter after crossing the border. They are really in a vulnerable position," said Lee.
She says human traffickers distribute the women for sale to husbands throughout northeast China - sometimes transporting them six and seven hours by train.
"And you simply don't know where you are. And you don't know where to run. And you know that you will be caught if you just run out to the street," Lee added. "And you don't want that, you don't want to go back to North Korea - you took a lot of suffering to cross the border, so you don't want to go back."
Lee says most of the men who buy the women are either physically or mentally disabled, and incapable of earning a living.
"The rural family or rural husband actually falls into debt because they had to pay a lot of money to buy this woman. So they are again in the poverty trap, which they really wanted to get out of with North Korea," noted Lee.
Some of the women flee - but most of them, says Lee, make do with their new lives - knowing at least that they will not starve.
"But the thing is, these women are young - in their 20's, 30's - and they become pregnant pretty soon. And they kind of give up the idea of running away. Things change - and they try to accept their fate," said Lee.
There are, by some estimates, as many as 50,000 North Korean women in China. Those women are believed to have had up to 20,000 children.
Human rights organizations say local governments in China are slowly starting to acknowledge the problem of trafficked North Korean women and their children. Some municipalities are beginning to register the mothers as members of Chinese families, to help them avoid arrest.
The central government, however, activists say, still downplays the problem. Beijing also refuses to allow the United Nations High Commissioner for Refugees formal access to North Koreans living in the country.