10. The Sasanian Empire
The Sasanian Empire, or also known as the last imperial dynasty in Persia. The Empire was before the rise of Islam and was considered to be the rival of the Roman-Byzantine Empire. The Empire was a leading world power for more than 400 years and was founded by Ardashir I. At the peak of the Sasanian Empire it had territories now known as Iran, Iraq, Eastern Arabia, the Levant, Armenia, the Caucasus, and parts of Turkey, Egypt, and a majority of Central Asia. The Empire was compiled of many different languages including Middle Persian, Middle Aramaic, Parthian, and Greek, as well as many different religions at one point. Needless to say it was a massive world power at one point.