A dolmen, also known as a portal tomb, portal grave, or quoit, is a type of single-chamber megalithic tomb, usually consisting of three or more upright stones supporting a large flat horizontal capstone (table), although there are also more complex variants. Most date from the early Neolithic period (4000 to 3000 BC). Dolmens were usually covered with earth or smaller stones to form a barrow, though in many cases that covering has weathered away, leaving only the stone "skeleton" of the burial mound intact.
It remains unclear when, why, and by whom the earliest dolmens were made. The oldest known dolmens are in Western Europe, where they were set in place around 7000 years ago, at the same time as the ancient civilisations of Egypt, India, and the Middle East. Archaeologists still do not know who erected these dolmens, which makes it difficult to know why they did it. The most widely accepted theory is that all dolmens are tombs or burial chambers. Human remains, sometimes accompanied by artifacts, have been found in or close to them, which could be scientifically dated. There is however no firm evidence that even this theory is correct. It has been impossible to prove that these archaeological remains date from the time when the stones were set in place.
Prehistoric Europe refers to the prehistorical period of Europe, usually taken to refer to human prehistory since the Lower Paleolithic, but in principle also extending to the geological time scale – for which see Geological history of Europe.
From the Lower Paleolithic, approximately 1.8 million years ago, and far into the Upper Paleolithic or 20,000 years ago, Europe was populated by Homo erectus and Homo neanderthalensis. In the Upper Paleolithic and Mesolithic, from about 43,000 to 6,000 years ago, Europe had Homo sapiens hunter-gatherer populations. During the last glacial maximum, much of Europe was depopulated and re-settled, about 15,000 years ago. The European Neolithic begins about 9,000 years ago in southeastern Europe, and reaches northern Europe by about 5,000 years ago.
The forerunner to the Bronze age where the Chalcolithic or Copper age and an archaeological site in Serbia contains the worlds oldest securely dated evidence of copper making at high temperature, from 7,500 years ago.