Following the Slavic migrations to the Balkans from the 6th century onwards, Serbs established several states in the early Middle Ages. The Serbian Kingdom obtained recognition by Rome and Constantinople in 1217; it reached its peak in 1346 as a relatively short-lived Serbian Empire. By the mid-16th century, the entire territory of modern-day Serbia was annexed by the Ottoman Empire, at times interrupted by the Habsburgs. In the early 19th century, the Serbian Revolution established the nation-state as the region's first constitutional monarchy, which subsequently expanded its territory. Following disastrous casualties in World War I, and subsequent unification of Habsburg crownland of Vojvodina with Serbia, the country co-founded Yugoslavia with other South Slavic peoples, which would exist in various political formations until the Yugoslav Wars of the 1990s, which had devastating effects for the region. As a result, Serbia formed a union with Montenegro in 1992, which broke apart in 2006, when Serbia again became an independent country. In 2008 the parliament of Kosovo, Serbia's southern province with an Albanian ethnic majority, declared independence, with mixed responses from the international community.