The principal outside cultural influences which came into Europe at different times followed four main routes: (1) from western Asia through Russia to central and western Europe; (2) from Asia Minor through the Aegean to Greece. and also through Thrace to central Europe; (3) from the Near East and the Aegean by sea to the western Mediterranean; and (4) from North Africa to Spain and western Europe. Thus the general direction of cultural movement was from south to north and from east to west; hence at any given moment in time the southern and eastern areas were apt to be enjoying a more advanced form of culture than were the more peripheral regions to the northwest. This is well illustrated by the course which developments took in each of the principal periods.
BC 8000- In the Mesolithic period, lasting for several thousand years, the Tardenoisian culture, which was most closely related to cultures in Africa and Spain and which was characterized by microlithic implements, spread from the south over most of Europe. At the same time, with the amelioration of the climate, there was a northward movement of peoples following the forests that gradually occupied the steppes and tundras of the North European plain and a forest culture was developed, characterized by the use of the chipped stone axe (Maglemosean and Ertebolle cultures).
BC 4000-3000. The Neolithic period had a similar gradual development. Neolithic culture appeared for the first time in Crete in the 4th millennium B.C. By 3000 B.c. some slight Neolithic influences had penetrated as far as western Europe from the east, via Russia, and from the south, via Spain. The earliest fullfledged Neolithic culture in Europe proper appeared in the Danube area of central Europe in the 3d millennium B.C., and spread from there to the Rhine Valley and throughout western Europe. Somewhat later the Megalithic culture, characterized by dolmens, passage graves, cists, and other rough stone monuments, spread along the coastal regions of western Europe from Spain to the Baltic.