Lead
In the long history of the earth, human beings were only a short-lived passerby, and human civilization did not even appear in the first four billion years of the earth, so some people believe that there may have been other civilizations on the earth before the birth of human beings, but they were buried, wiped out, forgotten, and disappeared by time.
This view is undoubtedly quite plausible, because there are indeed some strange phenomena on the earth, such as some super structures that resemble pyramids.
However, at present, the vast majority of geologists, biologists and archaeologists basically do not believe that there was a prehistoric civilization on the earth, let alone that there are intelligent beings on the earth that are the same as us or even more developed than us.
So, how likely is it that other civilizations once existed on Earth?
1. The existence of prehistoric civilizations.
It is obvious that the extent of human civilization is very limited today, and it is impossible to determine what the level of science and technology of previous generations of earth civilization was.
If the previous generations of civilizations did not have a high level of technology, or even the Stone Age, then this may really be a relic of civilization that we cannot explore, mainly because everything has been corroded, burned, weathered, and even cleaned up, so in this case, we can even ignore this possibility.
But if the previous generations of civilizations had not been much more technologically advanced than ours, or even more advanced than ours, then they would not have left a sporadic and insignificant trace on the ground—as if we would never have thought that this trace was made in Africa because of historical archaeology, because it could have been produced in countless other places, or in other ways.
This is actually known as the Occam's Razor Principle (the Occam's Razor Principle is a principle that guides people in scientific research and thinking, advocating the choice of the simplest explanation over the redundant one).
If there is anything left on Earth after the disappearance of human society, then we look at the volcanic rocks on the moon and other planets, which are the easiest similar artifacts to preserve other than the surviving buildings, and yet there is little indication that they were ever observed by intelligent beings.
In our first generation, almost a year before the Industrial Revolution, there were already a lot of large buildings, so even if we were only a hundred years before the technological advance, enough evidence could be found on the surface to prove it.
And if it were to develop for another 10,000 or even 10 million years...... Unless the level of technology of later human beings is low enough to be Stone Age, and all traces have been swept away by the laws of nature as huge as the scale of sand dunes, there will be a lot of evidence of this generation of human civilization and their architecture on the earth.
There has never been such a scene in the geological record, and in fact there are many interesting things in the geological record (such as the amount of oil produced in prehistory), and there is not a single mutation that feels strange at all.
So it is clear that if there was a period on earth before man, it was after man.