People referred to as Celts first appear, in Greek texts, during the period archaeologists call the Iron Age. This was the last phase of prehistory, which in Europe North of the Alps comprises roughly the last 600 to 800 years BC. The Iron Age conventionally ends with the gradual conquest of Western Europe and much of Britain by the Romans, which is taken to mark the beginning of recorded history. During these centuries, the Celts, also known as Gauls or Galatians, became the most feared of all the 'barbarian' peoples beyond the world of Greek and Roman urban civilization. Archaeology has shown that these peoples possessed vibrant cultures, and developed superb artistic styles. These peoples have another great claim to modern attention. The word 'Celtic' is used today of peoples whose present or former native tongues are related to those of the Ancient Celts. Most present Celtic-speaking peoples are in the Britain and Ireland, and these are widely referred to as Celts too. Among the most interesting aspects of the subject are the difficulty in defining exactly who the Ancient Celts were (and equally, who they were not), and just what relationship they have with the modern peoples often called 'Celtic'.