Bayezid I, also known as Yildirim (The Thunderbolt), was a sultan of the Ottoman Empire who reigned from June 1389 to July 1402. He is recognized in history as the founder of the first centralised Ottoman state in accordance with the traditional Turkish and Muslim institutions. In the initial years of his tenure, the Ottomans brought the vast Balkan territories under their control. Prompted by the increase of Venetian adventurism in Greece, Albania, and Byzantium, and expansion of Hungarian influence in Walachia and Danubian Bulgaria, Bayezid laid siege to Constantinople, subjugated Tirnova (in present-day Bulgaria), and vanquished Salonika. His attack on Hungary in 1395 led to the Hungarian-Venetian crusade against the Ottomans. In September 1396, the Christian forces suffered a decisive defeat at Nicopolis. To ensure the longevity and supremacy of his empire, Bayezid began to extend suzerainty over the Turkish-Muslim rulers in Anatolia. He conquered a number of Turkmen emirates in Anatolia and triumphed over the Karaman emirate at Akçay. These victories led to a war between Bayezid and the Central Asian conqueror Timur, the two most powerful rulers in the Islamic world at the time. In the climactic Battle of Ankara in 1402, Bayezid was defeated. He passed away about a year later while he was still Timur’s captive.