It's definitely not what I normally picture when I think about asteroids.

http://historyofgeology.fieldofscience.com/2011/04/landslide...

“[The tablet] is a copy of the night notebook of a Sumerian astronomer as he records the events in the sky before dawn on the 29 June 3123 BC”

But radiocarbon dating of trees buried in the landslide seems to have reliably dated the landslide to 7500 BC.

For example https://www.sciencedirect.com/science/article/abs/pii/S01695...

Update:

The Wikipedia article about the coauthor Mark Hempsell says:

“Hempsell got public audience as author of the book "A Sumerian Observation of the Köfels' Impact Event", with Alan Bond proposes a theory not accepted by the scientific community…”

The link posted in this thread by user arto calls the theory “pseudoscience”:

“Despite this new evidence, curiously in 2008 the impact hypothesis was revived by some pseudoscientists in connection to supposed observations of a meteorite by the Sumerians…”