The earliest form of the signature came from ancient Iraq in the form of cylinder seals.
Mesopotamians, the ancient inhabitants of the land between the Euphrates and Tigris rivers, are credited for many firsts in human history, including writing, urbanism and the state. Among these inventions, cylinder seals are perhaps the most distinctive but least known.
cm0002 in history
Signatures meant more in Mesopotamia than they do now: What cylinder seals say about ancient and modern life
https://phys.org/news/2025-11-signatures-meant-mesopotamia-cylinder-ancient.html