Born in Chongqing, Sichuan, Hsi went to Hong Kong at the age of five. She remembers reading in her fifth-grade textbook about Mongolian brutality, which gave rise to the Chinese folk custom of enclosing messages in moon cakes. (At the end of the Mongol-controlled Yuan dynasty, Chinese rebels tucked messages into moon cakes to notify each other of their anti-Mongol, revolutionary meetings.)
生於四川重慶，五歲時隨雙親轉赴香港，席慕蓉提及，小學五年級時，在歷史課本上讀到，蒙古人如何殘暴，故在元朝末年之際，有在月餅中夾「八月十五殺韃子」字條的風俗。