The earliest depiction of UFO like objects in ancient art are found in carvings in rocks on an island in Hunan Province, China.

They have been tentatively dated to an age of approximately 47,000 years.
This places them in the age of the Neaderthals.

UFO Evidence
Articles and documents related to the study of ancient alien contact

Additionally, physical evidence of an ancient alien vistation is seen in artifacts from around the world that show a use of modern technology.