After the collapse of Roman authority in the early fifth century, four major circles of political and cultural influence emerged in Northern Britain. In the east were the Picts, whose kingdoms eventually stretched from the river Forth to Shetland. In the west were the Gaelic (Goidelic)-speaking people of Dál Riata, who had close links with Ireland, from where they brought with them the name Scots. In the south were the British (Brythonic-speaking) descendants of the peoples of the Roman-influenced kingdoms of "The Old North", the most powerful and longest surviving of which was the Kingdom of Strathclyde. Finally, there were the English or "Angles", Germanic invaders who had overrun much of southern Britain and held the Kingdom of Bernicia (later the northern part of Northumbria), which reached into what are now the Borders of Scotland in the south-east. To these Christianisation, particularly from the sixth century, added Latin as an intellectual and written language. Modern scholarship, based on surviving placenames and historical evidence, indicates that the Picts spoke a Brythonic language, but none of their literature seems to have survived into the modern era. However, there is surviving literature from what would become Scotland in Brythonic, Gaelic, Latin and Old English.