2300 BCE Meteor Impact in Mesopotamia.

We seem to have another 'smoking gun' of an ancient catastrophe. This
one is an apparently meteoric impact from ca. 2300 BCE, one that is
spectacularly located: near the confluence of the Tigris and
Euphrates.

http://portal.telegraph.co.uk/news/main.jhtml?xml=/news/2001/11/04/wme
t04.xml&sSheet=/news/2001/11/04/ixhomef.html