There is nothing subtle about the freshly painted advert beside a road in suburban Taipei. It offers Vietnamese brides, guaranteed fertile, hard-working and Taiwanese-speaking. 'If she runs away we will replace her with a new bride of your choosing,' the advert promises. Yours for just US$8,500. Taiwan is importing women by the tens of thousands each year. While this large-scale immigration is straining social services and upsetting a few xenophobic conservatives, it is also helping to alleviate the twin problems of an ageing society and a declining birth rate. Taiwan's birth rate is the world's second lowest, at 1.2 births per woman. Meanwhile the elderly segment has grown, accounting for more than 9 per cent of the population. But a wave of unplanned immigration is slowing the greying trend. One in four marriages binds a foreign woman to a Taiwanese man, while one in every seven births is to an immigrant woman. While the government dawdled over crafting a population policy, hundreds of thousands of women from Southeast Asia and China have immigrated to Taiwan over the past decade. This back-door inflow has highlighted how slowly the government reacts to social changes. It also boosts the government's claims that Taiwan is not a monocultural Han Chinese society, but a diverse, multi-ethnic one. In a convenient twist, it was the traditional culture of the Han Taiwanese that initially drove this wave of marriage-based immigration. The traditional Taiwanese family is based on ample supplies of free female labour. As women became better educated and entered the workforce, they started having fewer children and stopped doing the laborious cooking, cleaning and religious observances that underpin Taiwan's sacred sense of family. To keep their households running, island matriarchs began arranging international marriages for their bachelor sons, who have been finding it harder to marry Taiwanese women. This was readily accepted, because women in traditional society were outsiders who integrated into the family by marriage. While this attitude has left some immigrant women isolated in abusive domestic situations, Taiwan's many civic organisations are working hard to teach these new citizens basic skills, like driving and literacy. And the new migrants are building their own support networks. When asked if she felt isolated, the proud owner of a Vietnamese noodle shop in Pingsi, a mountain village near Taipei, laughed and said 'no'. Two of her sisters and a childhood friend have also married into local families.