Hasan, a king of the city of Yathrib, in Arabia.  He was a tributary of Esarhaddon, who imposed a heavy tribute on his son Yala, by whom he was succeeded. (An Archaic Dictionary, Cooper, 1876).

... The third conspirator, Abdalrahman, repaired to Cufa, where, as Ali entered the mosque, he was felled to the ground by a fatal blow on the head, A.H. 40 (A.D. 660).  His body was buried five miles from Cufa; and in after times a magnificent tomb was erected over his grave, which became the site of a city, called Meshed Ali, or "the Sepulchre of Ali."  On his death his eldest son Hasan (i.e. "the Handsome") was elected to the Caliphate without opposition, but he resigned it in favour of Moawiyah, on condition that he should resume it on the death of the latter, who had the less scruple in assenting to the arrangement, owing to his secret determination that his son Yezid should be his successor... (The Miracle Play of Hasan and Husain, Pelly-Wollaston, v.1, 1879)