Last summer, a soft-spoken woman in her 40s who goes by Xiaocao got a tip that in Lüliang, a small city in China's Shanxi province, vulnerable women were being forced into marriages. So she and another volunteer did what any reasonable person would do: they left Beijing, traveled hours south by train and rental car, and started knocking on village doors. Most leads were dead ends. But on the final day, they found a woman with learning disabilities who had been "married" to two brothers.

"She could see we didn't mean any harm, so she stopped and chatted with us," Xiaocao says, requesting the nickname for obvious safety reasons. The woman declined help, but her case is one of potentially thousands that activists are quietly pursuing across China - not by shouting from rooftops, but by working in the shadows to support women they believe the state is failing.

This underground network gained momentum after the 2022 case of the "chained woman" - Xiao Huamei, a woman with mental illness who was found chained by the neck in a filthy shed, having given birth to eight children. Local officials initially defended her marriage to the man who tied her up. The case went viral despite authorities' efforts to contain it, and it sparked a new, clandestine brand of Chinese feminism.

The Chinese government says tackling trafficking is a priority. In 2021, it launched a 10-year anti-trafficking plan promising to "modernise and upgrade" investigation methods. In April this year, the Supreme People's Court claimed trafficking crimes involving women and children have dropped nearly 80% since 2012. But activists note that China has dramatically reduced the number of legal judgments available online, making it hard to verify those claims. A 2023 US government report noted that "some forced marriage cases … were mediated at the village level; these proceedings rarely culminated in a guilty verdict."

Since Xi Jinping took power in 2012, he has cracked down on civil society groups, including those fighting sexual harassment, domestic violence, and discrimination. Yet activists persist. Celine Liao, a PhD candidate at the University of Washington who studies feminism in China, says that before Xiao's case, "trafficking was not at the centre of mainstream feminist discourse" online. Now, "feminists and the broader public have become significantly more sensitive to trafficking-related issues."

In February, another case surfaced: a man in Guangxi's poor, mountainous region was discovered with a wife with learning disabilities, with whom he had nine children. "I dare not call this human trafficking. I have no evidence. But I want to ask: how could a woman with intellectual disabilities 'voluntarily' have nine children with a man?" wrote legal blogger Li Yuchen, in an article that was soon censored.

Women have responded in various ways. Some, like Xiaocao, physically travel to investigate exploitation reports. Others monitor anti-trafficking efforts in their spare time. A few have lobbied internationally - a highly risky move. Nearly all operate under anonymity, fearing retribution from authorities who treat independent activists harshly despite officially supporting the cause.

A Renmin University analysis of judicial case files from 2017 to 2020 found that 20% of more than 1,200 female trafficking victims had a physical or mental disability. Many cases, like the woman Xiaocao found in Shanxi, go unreported. In February, Free Nora - a media collective launched after Xiao's case - published an article marking its fourth anniversary, calling it "an indictment of the society and history we live in." The article and their WeChat account were later deleted.

Six people, including Xiao's husband, were convicted. Authorities launched a special operation that found over 1,000 missing women and children. But deeper investigations have been quashed. Activists note that Chinese law criminalizes buying and selling women, but doesn't cover cases where vulnerable women are forced into marriages. The Chinese government did not respond to a request for comment.

For now, Xiaocao is studying to be a lawyer to better advocate for women and children. "I don't think it's realistic to rely on the authorities to crack down on this," she says. So she'll keep doing what the system won't: one case at a time, in the shadows.