If you look at a map you see the Ottoman Empire centered in what is now Turkey, controling the sea route into the Black Sea, but also the coast areas of the mediterranean including what is now Lebanon, Israel, Efypt, Libya, also Saudi Arabia. At times the Empire controlled Greece and far into Europe. Thus the Ottomans controlled the trade and migration routes that crisscossed the area, that connected China and India to Europe and beyond. To trade east and west one had to do business with the Ottomans, which meant paying tolls and taxes to them, this wealth bought a great deal of power. The location was also strategic militarily for mcuh the same reasons. for centuries the Ottoman empire was a constant threat to Europe, the trading cities of Italy, even Russia.
