Complex sentence: During the Byzantine Age, Reggio became the capital of the "metropolis of the Byzantine possessions in southern Italy", and later capital of the Duchy of Calabria and linchpin of the Greek church in Italy.
Split into simpler sentences: During the Byzantine Age Reggio became the capital of the "metropolis of the Byzantine possessions in southern Italy". It was later made the capital of the Duchy of Calabria and linchpin of the Greek church in Italy.