Complex sentence: During the Middle Ages Rab was part of the Byzantine Empire, then, for a short time, part of the Kingdom of Croatia, then in 1358 the island came under the rule of King Louis the Great, the Angevin ruler of Hungary.
Split into simpler sentences: During the Middle Ages Rab was part of the Byzantine Empire, then, for a short time, part of the Kingdom of Croatia. In 1358 the island came under the rule of King Louis the Great, the Angevin ruler of Hungary.