When you think of those who lived on the American frontier, the sort of person who springs to mind is probably a rough-and-rowdy Caucasian cowboy with a scruffy face and spurs on his boots. But then there was Ah Toy – pronounced “Ah Choi” in Cantonese – who became one of the best-known Asian women in 19th century California. Ah Toy was the first recorded Chinese sex worker in San Francisco, but became much more: so successful was her chain of brothels that she often attracted unfriendly...