The island of Crete was one of the earliest centres of civilization in the Mediterranean. The remains at Cnossus show that the Bronze Age civilization called Minoan was highly developed and lasted from roughly 3600 to 1000 BC. On mainland Greece, a Bronze Age civilization, centred upon royal palaces such as those excavated at Mycenae, Tiryns and Pylos, developed somewhat later and lasted from about 1580 to 1120. The physical remains of these civilizations were largely unknown to the later Greeks, nor were there any written records available to later historians of the Classical period. In the opening chapter of his history of the Peloponnesian war, Thucydides, the most highly regarded of the Greek Classical historians, says that he has found it impossible, because of the remoteness in time, to acquire a really precise knowledge of the distant past or even of the history preceding his own period. In modern times the growth of archaeological science has enabled historians to fill in some of the gaps before the age of written records and also to supplement and sometimes to challenge the literary record. Examinations of burial sites and of their grave goods and of sanctuaries and their votive offerings have revealed patterns of settlement and trade. Not only do Minoan and Mycenaean pottery differ in style, but scientific analysis of the chemical composition of the pottery has enabled specialists to date it and to pinpoint its place of origin fairly precisely.