How did the boundaries of the byzantine empire change?

The Roman Empire consisted only the eastern half of the Roman Empire to begin with. During the 6th century, the Byzantine Empire expanded by conquering the vandal Kingdom in North Africa, and some part of Spain and Italy. The empire slowly lost its Spanish and Italian ownership, and for a time, many of the near eastern territory to Persia as well. The Persians were beaten by the Byzantines in the early 7th century but swiftly lost their African and near Eastern possession to the Arab armies. Their empire had slowly diminished to include an essential part of the Balkans by 700 CE. Finally, when Constantinople fell in 1453, nothing was left.

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