In 1402, he once more besieged Constantinople, appearing to find success, but he ultimately withdrew due to the invasion of the Mongol conqueror Timur.

In 1390, Bayezid took as a wife Princess Olivera Despina, the daughter of Prince Lazar of Serbia,[8] who also lost his life in Kosovo.

Bayezid recognized Stefan Lazarević, the son of Lazar, as the new Serbian leader - later despot - with considerable autonomy.

Upper Serbia resisted the Ottomans until Bayezid captured Skopje in 1391, converting the city into an important base of operations.

Forcible expansion into Muslim territories could have endangered the Ottoman relationship with the gazis, who were an important source of warriors for this ruling house on the European frontier.

Thus Bayezid began the practice of first securing fatwas, or legal rulings from Islamic scholars, to justify wars against these Muslim states.

However, Bayezid doubted the loyalty of his Muslim Turkish followers, so he relied heavily on his Serbian and Byzantine vassal troops in these conquests.

His major rival Sulayman, the emir of Karaman, responded by allying himself with the ruler of Sivas, Kadi Burhan al-Din and the remaining Turkish beyliks.

Nevertheless, Bayezid pushed on and overwhelmed the remaining beyliks (Hamid, Teke, and Germiyan), as well as taking the cities of Akşehir and Niğde, as well as their capital Konya from the Karaman.

At this point, Bayezid accepted peace proposals from Karaman (1391), concerned that further advances would antagonize his Turkoman followers and lead them to ally with Kadi Burhan al-Din.

Once peace had been made with Karaman, Bayezid moved north against Kastamonu which had given refuge to many fleeing from his forces, and conquered both that city as well as Sinop.

This proved unsuccessful: in 1396 the Christian allies, under the leadership of the King of Hungary and future Holy Roman Emperor (in 1433) Sigismund, were defeated in the Battle of Nicopolis.

In 1400, Timur succeeded in rousing the local Turkic beyliks who had been vassals of the Ottomans to join him in his attack on Bayezid, who was also considered one of the most powerful rulers in the Muslim world during that period.

This is the excerpt from one of Timur's letters addressed to the Ottoman sultan: Believe me, you are but pismire ant: don't seek to fight the elephants for they'll crush you under their feet.

[24] Sharafaddin Yazdi (d. 1454) in Zafar-nama wrote that Bayezid was treated with respect, and at his request, Turco-Mongols found his son among the captives and brought him to his father.

Ibn Arabshah wrote that "Bayezid's heart was broken to pieces" when he saw that his wives and concubines were serving at a banquet.

[53] In the words of the contemporary Greek historian Doukas:[54] [Bayezid] was a feared man, precipitate in deeds of war, a persecutor of Christians as no other around him, and in the religion of the Arabs a most ardent disciple of Muhammad, whose unlawful commandments were observed to the utmost, never sleeping, spending his nights contriving intrigues and machinations against the rational flock of Christ.... His purpose was to increase the nation of the Prophet and to decrease that of the Romans.

They embellished the legend that he was taken by Timur to Samarkand with a cast of characters to create an oriental fantasy that has maintained its appeal over the years.

Christopher Marlowe's play Tamburlaine the Great was first performed in London in 1587, three years after the formal opening of English-Ottoman trade relations when William Harborne sailed for Constantinople as an agent of the Levant Company.

A cycle of paintings in Schloss Eggenberg, near Graz in Austria, translated the theme to a different medium; this was completed in the 1670s shortly before the Ottoman army attacked the Habsburgs in central Europe.

[56] The historical novel The Grand Cham (1921) by Harold Lamb focuses on the quest of its European hero to gain the assistance of Tamerlane in defeating Bayezid.

[57] Bayezid (spelled Bayazid) is a central character in the Robert E. Howard story Lord of Samarcand,[58] where he commits suicide at Tamerlane's victory banquet.

In the 29th Degree of the Scottish Rite, Northern Masonic Jurisdiction, Bayezid appears as a central figure in a drama that is historical fiction.