Croatia is a country in Southeast Europe on the Adriatic Sea. It is bordered by Bosnia and Herzegovina, Serbia, Slovenia, Italy and Austria. The capital city is Zagreb. Croatia has a population of over 10 million people.Croatia was first mentioned in historical records in the 6th century AD. The Croats are a Slavic people who migrated to Croatia from the north. Throughout history, Croatia has been ruled by many different empires and kingdoms. After World War II, Croatia became an independent country and joined the European Union in 2007.