Hungary is a landlocked country in Central Europe located in the heart of the Pannonian Basin, a major agricultural area. Two major rivers cross the country from north to south: the Danube and the Tisza. Flat, fertile lands and rivers that facilitate trade explain why Hungary emerged as a regional power in the late ninth century; the combination also explains why Hungary attracted invaders. In fact, Hungary fell under partial Ottoman occupation between the 16th and 17th centuries, and then came under Habsburg rule. By the late 19th century, Hungary was part of the Austro-Hungarian Empire along with Austria. Hungary's modern borders were defined after World War I, when the country lost 70 percent of its territory and almost 60 percent of its population to its neighbors. The new borders led to a series of territorial and ethnic disputes that have not been fully solved. During the Cold War, Hungary was a Soviet satellite. Like most of its neighbors, Hungary joined NATO in 1999 and the European Union in 2004. Hungary is an exports-oriented, high-income economy, and one of the main receivers of foreign direct investment in Central Europe. Its main trade partners are in the European Union, and the country is a net receiver of EU cohesion funds. However, in recent years the Hungarian government has been critical of some aspects of EU integration, and has so far decided not to join the eurozone. Hungary is also interested in keeping close ties with its Central European neighbors in the Visegrad Group, which also includes Poland, the Czech Republic and Slovakia. While Hungary's main policy goal since the end of the Cold War has been to integrate into Western economic and security organizations, Budapest also seeks good ties with Russia, from whom it purchases most of its natural gas. After five centuries of being under the influence of bigger powers, Hungary's main geopolitical goal is to achieve as much autonomy as possible and to keep its options open, especially during times of competition between greater powers.