I would say the Hittites and the Celts. The Hittites thrived and disbanded before the beginnings of the Roman empire. The Celts were absorbed by the Romans but were keen to follow their ways.
The Hittites held battles with the Egyptian Empire, the Middle Assyrian Empire and the empire of Mitanni over control of the Near East.
The Flavian dynasty was a Roman imperial dynasty that rose to power during the Year of the Four Emperors, a civil war occurred in 69 AD. The Flavian Dynasty includes the reigns of Vespasian, Titus, and Domitian.
