the Celtic peoples Before the Roman Empire and the rise of Christianity, people lived in Iron Age Britain and Ireland, speaking languages from which the modern Gaelic languages (including Irish, Scottish Gaelic and Manx) and Brythonic languages (including Welsh, Breton and Cornish) descend. These people, along with others in Continental Europe who once spoke now extinct languages from the same Indo-European branch (such as the Gauls, Celtiberians and Galatians), have been retroactively referred to in a collective sense as the Celts, particularly in a wide spread manner since the turn of the 18th century. Variations of the term "Celt", such as Keltoi had been used in antiquity by the Greeks and the Romans to refer to some groups of these people, such as Herodotus' use of it in regards to the Gauls. The modern usage of "Celt" in reference to these cultures grew up gradually. A pioneer in the field was George Buchanan, a 16th-century Scottish scholar, Renaissance humanist and tutor to king James IV of Scotland. From a Scottish Gaelic-speaking family, Buchanan in his Rerum Scoticarum Historia (1582), went over the writings of Tacitus who had discussed the similarity between the language of the Gauls and the ancient Britons. Buchanan concluded, if the Gauls were Celtae, as they were described as in Roman sources, then the Britons were Celtae too. He began to see a pattern in place names and concluded that the Britons and Irish Gaels once spoke one Celtic language which later diverged. It wouldn't be until over a century later when these ideas were widely popularised; first by the Breton scholar Paul-Yves Pezron in his Antiquité de la Nation et de la langue celtes autrement appelez Gaulois (1703) and then by the Welsh scholar Edward Lhuyd in his Archaeologia Britannica: An Account of the Languages, Histories and Customs of the Original Inhabitants of Great Britain (1707). By the time the modern concept of the Celts as a people had emerged, their fortunes had declined substantially, taken over by Germanic people. Firstly, the Celtic Britons of sub-Roman Britain were swamped by a tide of Anglo-Saxon settlement from the fifth century on and lost most of their territory to them. They were subsequently referred to as the Welsh people and the Cornish people. A group of these fled Britain altogether and settled in Continental Europe in Armorica, becoming the Breton people. The Gaels for a while actually expanded,