The duration of Unas' reign is uncertain. As indicated above, historical sources credit him with 30 and 33 years on the throne, figures that have been adopted by many Egyptologists, including Flinders Petrie, William C. Hayes, Darrell Baker, Peter Munro, and Jaromir Malek. In favor of such a long reign are scenes of a Sed festival found in Unas' mortuary temple. This festival was normally celebrated only after 30 years of reign and was meant to rejuvenate the pharaoh's strength and power. Mere depictions of the festival do not necessarily imply a long reign, however. For example, a relief showing pharaoh Sahure in the tunic of the Sed festival has been found in his mortuary temple, although both historical sources and archeological evidence agree that he ruled Egypt for less than 14 full years.