Bunch of aggressive italians (yes I know it sounds funny but its true) who originated in Rome at the tail end of the Classical Era.
Gave shoeings to the Greeks (post Alexander), Carthaginians, French (obviously), Germans (pre panzers), Jews, Arabs, then inhabitants of England, Romanians and Spaniards. Gave up trying to conquer the Scots, Welsh, Irish ('cos it wasn't worth the effort) and the Persians ('cos they were too hard).
Stole anything they thought might help them conquer the known world be it weapon types, armour, troop types, religion or peoples. Displayed a total disdain for death whether their own or their enemies'.
Split into two seperate Empires (East and West) in the 4th century. The Western half fell in the 5th century after declining for a while. Went on to export Pizza, Pasta, Mafia and Religious War. The Eastern half (Byzantines) lasted till 1453 before the Turks kicked in their back doors (literally) and introduced kebabs and coffee to the western diet.