The Sassanids
Head of a Parthian (from the Louvre)
Like their Persian ancestors, these Sassanid Persians were Zoroastrians, and they also wanted to spread the Zoroastrian faith.
Arshashir
Shapur I, son of Ardashir
The leader of the Sassanids, by 227 AD the king of the Parthian Empire, was named Ardashir (the Greeks and Romans called him Artaxerxes). He organized a very strong and unified government. Then he took the army and invaded Roman territory in West Asia. Neither side won a clear victory, and this set the pattern for the next four hundred years: a lot of fighting but no real change in the borders.
To find out more about the Sassanids, check out these books from Amazon.com or from your library:
Ancient Persia, by Don Nardo (2003). For kids, good for reports.
Parthian Art, by Malcolm Colledge (1977). Not very easy to get anymore, but it's the classic book for the Parthians - it has a lot more than just the art.
Ancient Persia, by Josef Wiesehofer (2001). Includes the Parthians and the Sassanians.
Sasanian Society: Warriors, Scribes, Dehqans, by A. Tafazzoli (2000). An Iranian perspective.
The Cambridge History of Iran: Volume 3, The Seleucid, Parthian and Sasanid Periods, Part 2: Seleucid Parthian, edited by E. Yarshater (reprinted 1983). Expensive but complete.
