This has been answered before here. (edit: by u/Tiako)

To give a TLDR though, there are contemporary records of Enmebaragesi of Kish, and we have some evidence of Djoser of Egypt at the same time. Both of these are around 2600 BC. I will also add that Enmebaragesi was the 22nd king of Sumer, I believe, so the Sumerian King List accounts 21 more before him. Etana, the thirteenth king of Sumer, is the first to have their name mentioned in an another source, the Epic of Etana, though it is believed to be a folk tale.