Sunken Civ reported several years ago on a 2 mile diameter crater found when the Iraq marshes were drained. I believe the age mentioned was around 2,000 BC, or 4,000 years ago. Around that time the Egyptians experienced what is called The First Intermediate Period, a time of hunger and chaos as reported especially in the Ipuwer papyrus. That event must have had a very negative effect on many civilizations in the entire Southwest Asian/Middle Eastern/Mediterranean region. Most likely cooling after the initial burn.