I want to know the answer to the following question:
What empire were the controlled lands surrounding Constantinople formerly controlled by?
All the background I'm provided with is that "The empire had managed to control nearly all former Byzantine lands surrounding the city, but in 1402 the Byzantines were temporarily relieved when the Turco-Mongol leader Timur, founder of the Timurid Empire, invaded Anatolia from the east.". Is that enough to answer the question?