Archaeologists have uncovered various evidence of ancient "settled" (i.e., city-dwelling) civilizations going back into pre-history. Are there any markers that persist through enough time, so that we are relatively certain they are among the first? Is it possible or plausible that there have been others perhaps thousands or tens of thousands of years older, of which we have no evidence?
Note, apologies if this doesn't quite fit the sub.
The short answer is absolutely certain.
The longer answer is, as one can imagine, a bit more complicated.
Anatomically modern humans (i.e. people exactly like you and me) appear in the fossil record during the Middle Paleolithic Period, roughly 200,000 years ago[1]. These early humans lived in small kin groups (likely less than a dozen people) that survived through hunting and gathering. These individuals could use fire and created stone tools, much like hominins before them such as Homo Erectus, but they didn't create much else in the way of material culture. This way of life was largely unchanged until about 50,000 years ago, when abstract art, musical instruments, and ritual objects begin to appear in the archaeological record. This occurrence is often called 'Behavioural Modernity', a hotly debated term[2], but what is important for us to consider is that, around this time, the material culture of humanity begins to diversify in new and interesting ways.
The important point of all this is that most changes that humans make to the world around them, however small, leaves a detectable trace in the archaeological record. This is called Anthropogenic activity, so-called because it is done by humans, and it generally looks quite different from geologic, plant, and/or other animal activities. This is why we can see it. People tend to do stuff differently, so when humans start radiating out from eastern Africa, we see new sites all across northern Africa, Spain, the Levant, and western Arabia.
To get back to your interest in very old prehistoric civilizations, we know for certain that there were no cities during the Middle and Late Paleolithic (~300,000 to ~10,000 BCE), because we see the evidence of human occupation during that period. It is small-scale and still focused on seasonally mobile kin groups, much like it had been for the hominin species beforehand. What we start to see during the Neolithic Period (~10,000 - 4,500 BCE) is the emergence of a series of larger-scale human settlements that aren't necessarily cities, but have many of the features of them. These are sites such as Göbekli Tepe, Jericho, Talianki, and Çatalhöyük. During this period of time, humans begin practising agriculture, create the first pottery, and continue to develop diverse forms of architecture. The beginning of the next period is typified by the emergence of the first true cities (e.g. Tell el-'Oueili, Eridu, etc.).
I hope this answers your question.
[1] Shea, J. "Homo sapiens Is as Homo sapiens Was: Behavioral Variability versus 'Behavioral Modernity'" Current Anthropology 52.1 (2011): 1 - 35.
[2] The entire publication from the above footnote is devoted to discussing and dissuading the usage of this term.