From the Bible, which is a collection of records written in the first moment back to 1514 BC, one can make a sufficiently detailed human chronology to understand that Moses knew that the civilizations before him only went as far back as the same date as modern scholars likewise acknowledge, near 2.5 millennia before him.
How did Moses know that human civilization had begun at that time and in the same place where the modern science places it, if he had no way of measuring time before him by more than two thousand years? Did he have carbon clocks to measure ancient objects?

There are other questions about the first ancient civilization that I will analyze in this topic, such as: if evolutionists believe that the knowledge necessary for the appearance of a civilization is such a slow process, is it reasonable to believe that a first civilization would suddenly appear with everything that the Sumerian civilization had?
I suppose those who don't know first have to understand the real scope of the Sumerians as civilized human beings, so that they can then reason about how long it took them from a supposed archaic man in the style of evolutionary fiction, to men with advanced mathematics, knowledge of the skies, knowledge to transform the terrain, architecture knowledge, language and writing, literature with a high artistic level, ..., even schools for children.
Having started the subject... you already have to reason about the truth of the origin of civilized man: were they apes before the Sumerians? were they learning little by little before they suddenly built an empire like the Sumerian?
PS: We know about the Sumerian civilization from the writings of its time that have come down to us, and the testimony of people who lived long after that civilization ceased to exist, but who had evidence of its past.