His other son Bayezid was executed in 1561 on Suleiman's orders, along with Bayezid's four sons, after a rebellion. Although scholars no longer believe that the empire declined after his death, the end of Suleiman's reign is still frequently characterized as a watershed in Ottoman history. In the decades after Suleiman, the empire began to experience significant political, institutional, and economic changes, a phenomenon often referred to as the Transformation of the Ottoman Empire. Suleiman the Magnificent ( "Muḥteşem Süleymān"), as he was known in the West, was also called Suleiman the First ( "Sulṭān Süleymān-ı Evvel"), and Suleiman the Lawgiver ( "Ḳānūnī Sulṭān Süleymān") for his reform of the Ottoman legal system. It is unclear when exactly the term "Kanunî" (the Lawgiver) first came to be used as an epithet for Suleiman. It is entirely absent from sixteenth and seventeenth-century Ottoman sources, and may date from the early 18th century. Suleiman was born in Trabzon along the east coast of the Black Sea to Şehzade Selim (later Selim I), probably on 6 November 1494, although this date is not known with absolute certainty. His mother was Hafsa Sultan, a convert to Islam of unknown origins, who died in 1534. At the age of seven, Suleiman was sent to study science, history, literature, theology and military tactics in the schools of the imperial Topkapı Palace in Constantinople (modern Istanbul). As a young man, he befriended Pargalı Ibrahim, a slave who later became one of his most trusted advisers (but who was later executed on Suleiman's orders). At age seventeen, he was appointed as the governor of first Kaffa (Theodosia), then Manisa, with a brief tenure at Edirne. Upon the death of his father, Selim I (r. 1512–1520), Suleiman entered Constantinople and ascended to the throne as the tenth Ottoman Sultan. An early description of Suleiman, a few weeks following his accession, was provided by the Venetian envoy Bartolomeo Contarini:    Upon succeeding his father, Suleiman began a series of military conquests, eventually suppressing a revolt led by the Ottoman-appointed governor of Damascus in 1521.