Well, people started specializing in things and if they couldn't get something because they didn't know how to make it, they would trade for it. Fast forward 8000 years, companies like Coca Cola make coke and fanta and others can't make it because they're specialized for it. They trade for it with the entire world and other companies make things that Coca Cola owners buy.
A volcanic eruption or extreme flooding.
One of his accomplishments could be the defeat of Hannibal's brother Hasdrubal. This was at the battle of Baecula all the way back in 208 B.C. and within the next year was able to convince the local people of spain to pledge their allegiance to Rome.
In the battle of Zama he was able to defeat Hannibal through a funny turn of events. The Romans sounded horns that scared the Carthaginian elephants causing them to trample the troops.
I don't really have a third one off the top of my head but you could look up his military accomplishments since that is what he was known for. He was known for superior military abilities.
