Ramesses XI
The era was traditionally thought to have ended around its Year 10 (or Year 28 proper of Ramesses XI) when a letter from the corpus of Late Ramesside Letters shows that the High Priest Piankh was campaigning in Nubia. A graffito in Upper Egypt dates the return of Piankh to Thebes to the third month of Shemu day 23, "i.e." 3 days after the start of Ramesses XI's 29th regnal year, which would (on the assumption that the years of the Whm Mswt fully coincided with the original regnal years of Ramesses XI) prove that the Whm Mswt reached into a year 11.