Introduction – the roots of European languages
It is not exactly known, how the family of Indo-European languages spread into Europe and western Asia. Migrations and conquest may have caused this group to be present in central northern, south-eastern Europe as well as in the Near and Middle East1. There are several hypotheses about an event before the spread of Indo-European languages, that caused these movements of cultures and peoples.
According to one of the hypotheses (called “Pontic steppe hypothesis”), the war-like culture called Battle-Axe or Kurgan spread through conquest of passive farming populations. The main proponent of this theory was Lithuanian-born American archeologist Maria Gimbutas. She suggested that horse-riding warlike Kurgan had invaded Europe in the forth millennium BC and had given rise to secondary homeland of the Celtic, Italic, Germanic, Balto-Slavic Greek and other European branches, while conquests in the south and east produced Indo-European languages of India, Persia, Asia Minor, etc.2. Before the invasion of Kurgan Riders Europe was inhabited by agrarian tribes.
Map 1: Invasions of Indo-Europeans
Source: article “March of the Titans…”, www4.stormfront.org/whitehistory/hwr5.htm
An alternative theory by British archaeologist C. Renfrew indicates a population wave (due the increasing carrying capacity of the farming lifeway) that flooded the hunter-gatherer groups speaking the non-Indo-European languages who inhabited Europe. He located the original homeland of Pre-Indo-Europeans in Anatolia (modern Turkey). In his vision of expansion a slowly-growing population of farmers dispersed in Europe as early as 7000 BC3.
The Indo-Europeans who invaded (or dispersed in) Europe can be divided into four groups:  Celts,  Germans,  Balts and  Slavs. They arrived to Europe in waves from 4000 BC to 500 BC. Their original Homeland (according to booth “Pontic steppe” and Renfrew hypotheses) was the Black Sea Basin. Some theories mention the sudden climatic changes after the Glacial age as a reason for the migrations of Indo-Europeans.
In fact the climate changes may have had a little role in spreading of the farmers or post-neolithic warriors. Different processes could coincidentally have aided the spread of the Indo-European language family, at different times. Sudden climate change could have been the primary cause of migrations of Indo-European-speaking neolithic farmers or horse riding warriors. 4
Map 2: Possible origin of Proto-Indo-Europeans
One of the first waves of Indo-Europeans who arrived in Europe were Celts or proto-Celts, for it is difficult to define when Celts became a culture unto themselves5. Around 15000 –1000 BC, the Celts lived in an area which today is mostly in Eastern France. Until 600 BC Celts called Britanni occupied much of today’s France, parts of Belgium and Holland, Britain and Spain. The names Brittany and Britain are delivered from this group. The name Celts itself is much younger it comes from the world Keltoi, given to the Celtic tribes by Greeks. The Romans called Celts Galli or Gallus. The Celts Migrating westwards from their original homeland found the area inhabited by Old Europeans. In most regions Celts assimilated with the indigenous inhabitants. In France and Spain they mixed with well established Mediterranean population6. The Celts of Eastern Europe being fragmented came under the domination by the Germanic peoples. In medieval and modern times the Celtic tradition and languages survived in Brittany (Western France), Cornvall, Galicia (North Western Spain), Galatia (Central Turkey), Wales, The Scotish Highlands, Isle of Man and Ireland, and to lesser extent in Norse/Celtic culture of Iceland7. From 1800 to 400 BC Celts in southern Germany and Austria developed two advanced metalworking, named after the places where their artifacts were found. These cultures were Urnfield and Hallstatt8.
In the first half of first millennium BC Gauls (of Celtic origin) from beyond the Alps began to penetrate the Northern Italy. In 8th century BC the tribe of Etruscans (who were of the Non-Indo-European origin) began to take form in Central Italy. Already in the Copper Age the area of the Alban Hills, to the south of the month Tiber, was inhabited by an Italic agricultural and pastoral tribe called Latini (possibly of the Celtic origin). And it was due to them9 in all probability, that Rome was founded towards the middle of the 8th century BC on one of the numerous hills (the Palatine) in the marshy depressions surrounding the river.
The first group of Indo-Europeans to enter the Greek mainland were Mycenae10. They absorbed the group of Old European Mediterranean types. Myceanean are regarded as the forerunners of the classical Greek civilization. Another Indo-European tribe called Dorics invaded and destroyed the city of Mycenae 1100 BC. The later Greek language in the historical period divides itself into several dialects which are largely mutually intelligible, but these are in turn replaced by politically dominant Athens with Attic Greek, the language of the culture from then on11.
The next wave of Indo-Europeans invading Europe were Germans. They settled in today’s Denmark and southern Scandinavia and moved south to central Europe. By the 7 century BC they had begun a division into many peoples. They did not call themselves Germans, the origin of the name is uncertain. Although the earliest mention of the Germans is by a Greek navigator who saw them in Norway and Jutland in the 4 century BC, their real appearance in history began with their contact (1st century BC) with the Romans. As the centuries passed the Germans became increasingly troublesome to the Roman Empire. The Vandals in the west and the Ostrogoths in the east were the first to attack the empire seriously. The Ostrogoths were a part of the Gothic people, often called the East Germanic, whose language (Gothic) was the first written Germanic language. The Goths apparently moved south-eastwards from the Vistula River to the Balkans, then westwards across Europe12.