Amorite Conquest
If you're one of the select few list readers who doesn't skip the introductions, you surely noted that the first Babylonian Dynasty was referred to as "Amorite," even if it's unlikely that you knew what that term meant. As it turns out, a group of raiders looking for a place to graze their horses was the very unexpected catalyst for Babylon's rise to prominence as one of Ancient Mesopotamia's largest and unquestionably most renowned civilizations.
The Amorites were a nomadic people who originated in what is now Syria. They were taken into Mesopotamia by their chieftains, who were mostly looking for pasture land. Although several of the surviving Sumerian narratives belittle them for not even being technologically advanced enough to "know grain," the primitives emerged victorious after defeating both the Sumerians and the Babylonians.
This may resemble tales of the barbarians that attacked Rome in its early years of existence or the Mongols, who established the biggest empire in history. While not an agricultural society, the Amorites were distinct in that they established long-lasting rule over the towns they conquered. The hot-blooded nomadic lifestyle of the Babylonians may have contributed to their development into one of the first empires, but because there were five kings between their conquest of Babylon and Babylon's rise into an empire, those genes must have been extremely recessive.