When Iris Chang was a child, she was told by her parents, who had escaped with their families from China via Taiwan to the United States after World War II, that during the Nanking Massacre, the Japanese "sliced babies not just in half but in thirds and fourths." In the introduction of The Rape of Nanking, she wrote that throughout her childhood, the Nanking Massacre "remained buried in the back of [her] mind as a metaphor for unspeakable evil." When she searched the local public libraries in her school and found nothing, she wondered why no one had written a book about it.
The subject of the Nanking Massacre entered Chang's life again almost two decades later when she learned of producers who had completed documentary films about it. One of the producers was Shao Tzuping, who helped produce Magee's Testament, a film that contains footage of the Nanking Massacre itself, shot by the missionary John Magee. The other producer was Nancy Tong, who, together with Christine Choy, produced and co-directed In The Name of the Emperor, a film containing a series of interviews with Chinese, American, and Japanese citizens. Chang began talking to Shao and Tong, and soon she was connected to a network of activists who felt the need to document and publicize the Nanking Massacre. In December 1994, she attended a conference on the Nanking Massacre, held in Cupertino, California, and what she saw and heard at the conference motivated her to write The Rape of Nanking. As she wrote in the introduction to the book, while she was at the conference, she was "suddenly in a panic that this terrifying disrespect for death and dying, this reversion in human social evolution, would be reduced to a footnote of history, treated like a harmless glitch in a computer program that might or might not again cause a problem, unless someone forced the world to remember it."