the weak Muslim kingdoms beyond the Awash River. Similar campaigns in the north against the Agaw and the Falasha were not as successful. The first time the title of the coastal regions' ruler, Bahr Negash, appears is during the reign of Emperor Zara Yaqob, who perhaps even introduced that office. After witnessing a bright light in the sky (which most historians have identified as Halley's Comet, visible in Ethiopia in 1456), Zara Yaqob founded Debre Berhan and made it his capital for the remainder of his reign. In his later years, Zara Yaqob became more despotic. When Takla Hawariat, abbot of Dabra Libanos, criticized Yaqob's beatings and murder of men, the emperor had the abbot himself beaten and imprisoned, where he died after a few months. Zara Yaqob was convinced of a plot against him in 1453, which led to more brutal actions. He increasingly became convinced that his wife and children were plotting against him, and had several of them beaten. Seyon Morgasa, the mother of the future emperor Baeda Maryam I, died from this mistreatment in 1462, which led to a complete break between son and father. Eventually relations between the two were repaired, and Zara Yaqob publicly designated Baeda Maryam as his successor. Near the end of his reign, in 1464/1465, Massawa and the Dahlak archipelago were pillaged by emperor Zara Yaqob, and the Sultanate of Dahlak was forced to pay tribute to the Ethiopian Empire. According to a manuscript written in 1784, Zara Yaqob persecuted many idolaters who admitted to worshipping pagan gods such as Dasek, Dail, Guidale, Tafanat, Dino and Makuawze. These idolators were decapitated in public. Spies also revealed that his sons Galawdewos, Amda Maryam, Zar'a Abraham and Batra Seyon, and his daughters Del Samera, Rom Ganayala and Adal Mangesha were all idolators and thus they were all executed as a result. In the sixteenth century Adal leader Ahmed ibn Ibrahim al-Ghazi ordered the destruction of his former palace in Debre Birhan. Ethiopian Church When Zara Yaqob assumed the throne, the Ethiopian Church had been divided over the issue of Biblical Sabbath observance for roughly a century. One group, which was loyal to the Coptic Orthodox Church of Alexandria, believed that the day of rest should be observed only on Sunday, or Great Sabbath. Another group, the followers of Ewostatewos, believed with its founder that both the original seventh-day Sabbath (Saturday, or Lesser Sabbath)