Complex sentence: In the 3rd century the Roman emperor Diocletian split the Tarragonensis province in three and the Gallaecia province was created, western Hispania was then made of Lusitania in the south and Gallaecia in the north.
Split into simpler sentences: In the 3rd century the Roman emperor Diocletian split the province of Tarraconensis into three, creating the province of Gallaecia. Western Hispania was then made up of Lusitania in the south and Gallaecia in the north.