These are not the only, or even the best forms of evidence of the existence of poleis in the archaeological record.
Instead, we can look to physical evidence found by archaeologists. For example, there are many signs that cities were being developed in organized ways. There is evidence that the cities were laid out in planned ways and had things like public works and public spaces. In addition, we see evidence that the population of the countryside had been declining in a peaceful way. These people were, evidently, moving to the cities.
These things do not directly prove that the cities were organized into poleis. However, we do see that cities were becoming the major centers of population and apparently of government. This implies that they were organized into poleis.
The first written records suggesting the existence of a Greek Polis began to appear around the 9th century BC as the Greeks had adopted the Phoenecian alphabet and changed it into what would become the Greek alphabet.
Evidence of the Greek civilization comes mainly from archeological evidence that suggests various developments equated with Greek civilization. There are also records and archeological evidence of various conflicts between Greek city states and outside forces. Some of the main pieces of evidence involve statues and other forms of Greek gods that were worshipped at the time.