Any question about influences on Hamlet probably have to start with Ur-Hamlet, a lost play which was written mere decades before William Shakespeare's Hamlet, and has a very similar plot. Other principal sources available to Shakespeare were Saxo Grammaticus’s Historiae Danicae (circa 1200), which features a popular legend with a plot similar to Hamlet, and François de Belleforest’s Histoires Tragiques, which provides an expanded account of the story recorded in the Historiae Danicae.