Discovery of Greek Bronze Age

The Classical Greeks sought their own origins in the legends of gods and heroes. It was not until the discipline of archaeology emerged, in the nineteenth century, that the evidence of material culture could be used to form an image of the earliest societies in Greek lands. Only in the last 125 years have the Cycladic, Minoan and Mycenaean peoples been brought o light and an elaborate framework of dates, styles, periods and events constructed to enable us to understand the Aegean Bronze Age. 

Where have these facts come from, and how accurately do they actually describe a remote period of from which there is no written history ?