Under Heaven is the eleventh novel by Canadian fantasy author Guy Gavriel Kay. It was published in April 2010 by Viking Canada. Set in a fantasied Tang China, it is Kay's first work set outside of a fantasied European or Mediterranean setting. The novel is based on a fictionalized version of the An Shi Rebellion. Under Heaven takes place in a completely new world, as seen by it having only one moon as opposed to the two moon normally present in Guy Gavriel Kay's works.