Istanbul in the 1970s, as people from Anatolia migrated to the city to find employment in the many new factories that were built on the outskirts of the sprawling metropolis. This sudden, sharp rise in the city's population caused a large demand for housing, and many previously outlying villages and forests became engulfed into the metropolitan area of Istanbul. Istanbul is located in north-western Turkey within the Marmara Region on a total area of . The Bosphorus, which connects the Sea of Marmara to the Black Sea, divides the city into a European, Thracian side—comprising the historic and economic centers—and an
Strait of Tartary (1832–54). On Russian maps, the short narrowest section of the strait (south of the mouth of the Amur) is called Nevelskoy Strait, after Admiral Gennady Nevelskoy, who explored the area in 1848; the body of water north of there, into which the Amur River flows, is the Amur Liman; and the name of "Strait of Tartary" is reserved for the largest section of the body of water, south of Nevelskoy Strait. The Tartar Strait was a puzzle to European explorers since, when approached from the south, it becomes increasingly shallow and looks like the head of a bay. In 1787