A region between the Black and Caspian Seas that includes southwest Russia, Georgia, Azerbaijan, and Armenia, and that forms part of the traditional boundary between Europe and Asia. Inhabited before 2000 BC, it was the scene of countless invasions over the millennia. Conquered by Russia during the 1700s and 1800s, the region has vast oil resources, which were a major German objective in World War II. Following the collapse of the USSR in 1991, the region became the site of various secessionist movements.