jats:pThe kingdom of <jats:styled-content style="fixed-case">S</jats:styled-content>trathclyde was focused on the <jats:styled-content style="fixed-case">C</jats:styled-content>lyde valley and ruled by a Brittonic‐speaking dynasty. Historians have traditionally argued that the kingdom expanded southwards in the early tenth century, with the result that there was a revival of Brittonic language. Several scholars have recently challenged this interpretation, but in this article I defend the view that <jats:styled-content style="fixed-case">S</jats:styled-content>trathclyde expanded southwards, and I propose a new model for the process. I argue that the kings of <jats:styled-content style="fixed-case">S</jats:styled-content>trathclyde took submissions from the local nobility, who included <jats:styled-content style="fixed-case">N</jats:styled-content>orthumbrian and <jats:styled-content style="fixed-case">G</jats:styled-content>aelic‐<jats:styled-content style="fixed-case">S</jats:styled-content>candinavian magnates. This accounts for the multicultural nature of the kingdom in its heyday.</jats:p>