Final answer:
Vahan may hate Sivas due to its historical destruction by Timur in 1400, which weakened the Ottoman Empire and isolated Bayezid from potential allies, while Timur allied with the Byzantines.
Step-by-step explanation:
The question pertains to the historical enmity between Vahan and the city of Sivas, which is rooted in the events of the early 15th century. In 1400, the fearsome conqueror Timur launched an attack and destroyed the city of Sivas, which was under the control of Bayezid's Ottoman Empire. This devastating act not only weakened Bayezid's rule but also isolated him geopolitically by preventing him from seeking aid from the Mamluk sultans in Egypt and Syria. Moreover, Timur's strategic alliance with the Byzantines further encircled the Ottomans, consolidating forces from different regions to rise against them.