Start as Trajan (Rome), use the True Start Location Europe map and set the Disaster Intensity to 4. You can change the game speed to Online to make this quicker.
When the game loads, move your Settler one tile south-east and found your city.
Now it's a case of growing Rome (your city) as quickly as possible by gathering food. Build Builders to make farms and use your Traders to garner food via trade routes. When Rome grows to a population of 7 or above, it's just about waiting for Vesuvius to erupt. Depending on the intensity of the eruption, it should eliminate 6 of your population where the achievement will unlock.