 According to the work "De Administrando Imperio" written by the 10th-century Byzantine Emperor Constantine VII, the Croats arrived in the area of modern-day Croatia in the early 7th century.However, that claim is disputed, and competing hypotheses date the event between the 6th and the 9th centuries.Following the establishment of a personal union of Croatia and Hungary in 1102, and the joining of the Habsburg Empire in 1527, the Hungarian and German-speaking population of Croatia began gradually increasing in number.