Conditions in Central and Western Europe differed greatly from those in the steppes. In a region that was then heavily forested, the expansion of various Indo-European peoples continued from the 2nd millennium BC. In the first few centuries after 1000 BC, it was especially the ancestors of the later Celts who spread to the West and Southwest as far as Spain and the British Isles. In these years, the use of iron, which had been derived from the older civilizations in the eastern Mediterranean, especially in Anatolia, became well known in Italy and the Alps region, and spread from there since the 7th century BC to the whole of Western Europe. Here, the so-called Halstatt culture (named after an archaeological site in Austria) arose, characterized, among other things, by fortified hilltop settlements (in German: Herrensitze). Perhaps, the use of iron, like the use of bronze in an earlier period, deepened an already existing social divide between the warriors and their leaders on the one hand and the mass of the peasant population on the other, stimulating an appetite for plunder and conquests in those who possessed the metal weapons.
In expanding over Europe, peoples such as the Celts and the Illyrians would in its southern regions come into contact with the urbanized civilizations on the shores of the Mediterranean Sea. Unlike the nomads of the Eurasian steppes, these Indo-European groups mainly wanted places for themselves to settle in within this—for them—alluring Mediterranean world. On their part, the Mediterranean urban civilizations would ultimately absorb many of their European neighbors, because these essentially were sedentary societies too, not differing greatly in their basic social structures. But in the first half of the 1st millennium BC, these developments were still to come. In that period, urbanized culture was still limited to a few Mediterranean regions. In the first two or three centuries after 1000 BC, the Phoenicians from present-day Lebanon explored the coasts of the Mediterranean as far as Spain and established trading posts at various spots. Their colony Carthage, founded in the 9th century BC on the north coast of Africa, would in the following centuries even develop into a great commercial and political power. Meanwhile, the Greek world, after its decline as a consequence of the fall of the Mycenaean civilization, experienced from around 900 BC a steady revival under the influence of the Near East. As a result, an urban and literate society appeared in Greece in this period. In the 7th and 6th centuries BC, partly under Greek influences, such a society took root among the Etruscans in Central Italy as well. Brought by Phoenician, Carthaginian, Etruscan, and Greek traders, bronze objects, luxury ceramics, wine, and other articles from the “civilized” urban world found their way to the chieftains in the interior of Central and Western Europe in exchange for silver, tin, or slaves. As a consequence, the differences in wealth and prestige within these European societies increased, while princes and their retinues of warriors were motivated to attempt further plundering raids, especially in a southerly direction.