If you want to talk about real expansion and diversity, you've got to talk about the Punic Wars. These were the wars that I remember primarily because they involved Hannibal crossing the Alps with freaking war elephants, which was probably the last time that the elephants could have risen up and formed their awesome secret elephant society with elephant planes and elephant cars. In the first Punic War, Rome wanted Sicily, which was controlled by the Carthaginians. Rome won, which made Carthage cranky, so they started the second Punic War. In 219 BCE, Hannibal attacked a Roman town, then led an army across Spain, and then crossed the freaking Alps with elephants. Hannibal and his elephant army almost won, but alas, they didn't, and as a result, the Romans got Spain. People in Spain are definitely not Romans, despite Russell Crowe's character in Gladiator, which means that by 201 BCE, Rome was definitely an empire.