River Clyde is a river that flows into the Firth of Clyde in Scotland. It is the ninth-longest river in the United Kingdom, and the third-longest in Scotland. It runs through the major city of Glasgow. Historically, it was important to the British Empire because of its role in shipbuilding and trade. To the Romans, it was Clota, and in the early medieval Cumbric language, it was known as Clud or Clut. It was central to the Kingdom of Strathclyde.