Hannibal was a Carthaginian military commander who first-hand experienced the overwhelming tension between Carthage and Rome. When the Emperor Tiberius was overthrown the Praetorian Guard auctioned the throne to the highest bidder for years.
These invasions led to famine and robbery in Western Rome.
Once the Roman Emperors denied the right of free worship, Romans became angered. Hannibal had a prime opportunity to defeat the seemingly invincible civilization of Rome, but failed to do so due to flawed execution of his original tactics.
It spanned from the western shores of what is now Portugal, to as far as the modern day Persian Gulf to the east.
They ultimately failed to provide enough goods for their increasing population and troops. Commodus was a poor leader causing civil wars and tribes around the Mediterranean to invade.