The island of Rhodes has been inhabited since Neolithic times, and was home to major cities built by the Dorians in the 16th century BC. It joined the Athenian League after the Persian Wars and the island united in the 5th century BC to build the city of Rhodes. Rhodes fell under the control of various empires throughout its history, including the Romans and Byzantines, and the Knights Hospitaller built the Grand Palace before it was conquered by the Ottomans. The island was assigned to Italy after World War I and its Jewish population was sent to concentration camps by the Nazis during World War II, before Rhodes officially joined Greece in 1947.