The act of kidnapping someone and selling them into prostitution. The term came into use in Victorian times, during a panic in which it was believed that any woman could be kidnapped off the street, shipped off to the mysterious Orient, and forced to commit unspeakable acts for their evil Chinese masters.
Obviously, the practice of kidnapping women and forcing them to become prostitutes likely pre-dated the Victorians, but a number of pulp fiction exposés fanned the flames of a growing xenophobic hysteria about the Yellow Peril. The panic soon spread to other parts of the world, gaining significant popularity in America.
In fact, Asians had some fears that degenerate Americans or Europeans would kidnap their women -- xenophobia knows no boundaries...