Three-year-old Wenwen returned home last week after being reported missing for about 50 hours.
The boy was kidnapped while playing near his house, a room rented by his parents, in Xiegang town of Dongguan. Police rescued him from a person's home 400 km away, where kidnappers had sold him for 18,000 yuan ($2,630).
Wenwen is one of the four children Dongguan police have rescued recently, taking the total number since 2000 to 138.
"But 121 kidnapping cases are yet to solved," said Li Zhuohua, a Dongguan police officer. The huge population of migrant workers in the manufacturing city has made it easy for kidnappers to target their children.
Kidnapping became rampant around 2000, Li said, and is reported often even now.
The method kidnappers seem to favor the most is befriending kids with the promise of giving them toys or candies if they follow them to a certain spot. Others make friends with a targeted child's parents. They abduct the kid as soon as the parents drop their guard.
The more daring ones just lift a child when its parents are not watching. Wenwen's kidnappers employed this method. "My son was 'lost' in the blink of an eye," his father Zhou Hua said.
Zhou was lucky because neighbors reported to police that they had seen a suspicious looking woman surnamed Zhang loitering around his house. Police picked up the woman, who helped them track down the child.
Zhou should thank the Ministry of Public Security, too, which began a 9-month nationwide campaign last month to prevent kidnapping of women and kids. Since then police have taken significantly less time to rescue kidnapped children.
Last week, the authorities launched a nationwide DNA databank to help identify abducted children and return them to their families. Medics will collect blood samples of parents who report their kids missing and store them in the databank.
This will allow scientists to match the DNA samples of suspected kidnap victims or homeless kids found loitering or begging on streets with that of the parents' in the databank, the ministry said.
Earlier, the ministry had said 2,000-3,000 cases of women and children being sold were reported across the country every year. Experts say the figure is much higher, though.
"It's very hard to offer a specific figure," said Jiang Feng, China coordinator of the UN Inter-Agency Project (UNIAP) on Human Trafficking in the Greater Mekong Sub-region. "But from our observation, we don't see kidnapping cases dropping in China."
The domestic route of human trafficking is usually from the less developed west to the developed east, Jiang said. Boys are usually sold to families that don't have a son, and girls either become victims of sexual assault or grow up to be sold as "wives" of men who cannot pay a hefty dowry to get a bride.
Yunnan province and the Guangxi Zhuang autonomous region report the highest number of cross-border human trafficking cases. Women are kidnapped from there and taken to Myanmar, Vietnam or Laos and sold as "wives". Women are abducted from those countries, too, and sold in Yunnan and Guangxi.
Kidnapping is closely related to the migrant population, Jiang said. The large floating population makes it easy for kidnappers to target their victims.
National Population and Family Planning Commission data show the country's migrant population was 200 million last year. It is likely to increase to 500 million in the next 30 years.
Dongguan police officer Li conceded that the huge migrant population in the city made it difficult to rescue abducted kids. "Many of the kidnappers flee to their remote hometowns or are lost in the sea of people in other towns."
Jiang suggested a long-term mechanism be set up to end the problem permanently. But "it's not a problem that can be solved by police alone Central government ministries have to join hands and more information has to be shared."
The UNIAP is pushing 29 ministerial-level agencies to set up a coordinated mechanism, and it is necessary that the Criminal Law is revised to ensure people who buy abducted kids are punished too, Jiang said.
Under the existing law, criminal charges cannot be brought against people who buy abducted kids.
Zhang Baoyan, director of website Baby Come Home that helps parents find their missing children, said buyers should get heavier punishment than kidnappers.
"They're at the root" of the problem, she said. "As long as there is a market, some people will always take the risk" of abducting kids and women.
More than 2,000 parents are seeking the help of her website to find their missing children, and about 500 children are looking for their family.