Achaea remained a province of the Byzantine Empire after the fall of the western Roman Empire. In the 6th and 7th centuries, Slavs invaded the Peloponnese, and settled in parts of Achaea as well. By the 9th century, the whole peninsula was under Byzantine control again. However, after the Fourth Crusade several new crusader states were founded in Greece. One of these was the Principality of Achaea, founded in 1205, which like the Roman province covered a much larger area than traditional Achaea. Achaea was recaptured by the Byzantine Empire by 1430, and became part of the Despotate of the Morea.