Dunno. Maybe these artifacts survived the flood or maybe the accuracy of the artifact dating needs to be verified.
I'm not talking about artifacts dated using radiocarbon methods. I'm talking about WRITTEN RECORDS of civilizations existing around the period of the Flood ( ~ 2500 BC, give or take), such as the Sumerians of the Babylonian region, and the Egyptians, which talk about dynasties, events, etc, but strangely make no mention of any world-destroying Flood happening right in the middle of their time lines.
When you have civilizations making written records, dating from hundreds of years before the Flood, to well after the Flood, civilizations comprising millions of people, one would think that there would be some indication or note about, well, EVERYBODY BEING WIPED OUT, and the civilization having to be repopulated by the descendents of Noah, who oddly just continued the writing styles of the civilizations who were there before the Flood, did so without interruption, and made no mention in their writings of any Flood.