Ahmed I (ä´mĕd), 1589–1617, Ottoman sultan (1603–17), son and successor of Muhammad III to the throne of the Ottoman Empire. The chief event of his reign was the Treaty of Zsitvatorok (1606), which supplemented the Treaty of Vienna between Archduke (later Holy Roman Emperor) Matthias and Prince Stephen Bocskay of Transylvania. By the treaty, the emperors, as kings of Hungary, ceased to pay tribute to the sultan, and Transylvania was recognized as independent. The treaty also marked the first time the sultan recognized other European rulers as his equals. In the Asian provinces, disorders were suppressed by Ahmed's vizier, the Croatian Murad Pasha. After Murad's death (1611) problems again arose, allowing Shah Abbas I of Persia to retain Tabriz. On becoming sultan, Ahmed had not killed his brother Mustafa as was the custom; hence, Mustafa I succeeded as the oldest male in the ruling family. Ahmed I is also noted for the building of the Blue Mosque in İstanbul.