Chinatown in Singapore. [Photo by Tan Wei Ann/For China Daily]

The Samsui women, although not bound by vows of celibacy, were in many cases forced into spinsterhood due to a lack of suitable men to marry.

With their families always uppermost in their minds, these women sent home every penny they could save. However, one of the few things they spent their money on was on hiring professional letter writers to communicate with their loved ones back in China.

According to Chu, both groups of women passed into history as Singapore began its journey to becoming the rich, modern and super-clean city-state that people know today.

By the 1970s, many mah-jie had gone into retirement, replaced by domestic helpers from neighboring countries such as the Philippines.

The jobs for the Samsui women lasted a little while longer: Some of them, who were already in their 60s and 70s then, continued to toil at construction sites right up to the 1980s, when their jobs were taken over by machines.

"The stories of these women were lost before they were unearthed by a society which decided to say a belated thank-you to them," says Chu.

"There are now organizations which help to pay for these women to visit their hometowns in China, sometimes for the first time since their arrived in Singapore and probably the only time before they die."