Croatia, officially the Republic of Croatia, is a country situated at the crossroads of Central and Southeast Europe, on the Adriatic Sea. Its capital city is Zagreb, which forms one of the country's primary subdivisions, along with its twenty counties. Croatia has a total area of 56,594 square kilometres and a population of 4.28 million, most of whom are Roman Catholics.
The Croats arrived in the area of present-day Croatia during the early part of the 7th century AD. They organised the state into two duchies by the 9th century. Tomislav became the first king by 925, elevating Croatia to the status of a kingdom. The Kingdom of Croatia retained its sovereignty for nearly two centuries, reaching its peak during the rule of Kings Petar Krešimir IV and Dmitar Zvonimir. Croatia entered a personal union with Hungary in 1102. In 1527, faced with Ottoman conquest, the Croatian Parliament elected Ferdinand I of the House of Habsburg to the Croatian throne. During the early 19th century, parts of the country were split into the French Illyrian Provinces, and Austria-Hungary occupied its Bosnia and Herzegovina side–a dispute settled by the 1878 Treaty of Berlin.