Geoffrey Wheatcroft writes:
At its high tide under Suleiman the Magnificent and his immediate successors, the Ottoman Empire stretched from the Persian Gulf in the south to the Balkans in the north and reached the gates of Vienna in 1683. Then came the long ebb, as the Turks retreated from Europe and others competed to replace them. One power in particular had grown rapidly in importance. The small medieval principality of Muscovy had expanded hugely: Russia reached the Black Sea in the 18th century, picked up the larger portion of Poland when it was partitioned, and was soon standing on the Ottoman border, casting a hungry eye over what are today Romania, Bulgaria and Serbia.