Sub-Roman Britain is the period of late antiquity on the island of Great Britain, covering the end of Roman rule in the late 4th and early 5th centuries, and its aftermath into the 6th century. The term "sub-Roman" was originally used to describe archaeological remains such as potsherds found in sites of the 5th and 6th centuries, and hinted at the decay of locally made wares from a previous higher standard that had existed under the Roman Empire. It is now more often used to denote this period of history instead. The term Post-Roman Britain is also used, mainly in non-archaeological contexts.
Although the culture of Britain in the period was mainly derived from Roman and Celtic sources, there were also Saxons settled as foederati in the area, originally from Saxony in northwestern Germany. Saxons and other Germanic peoples gradually assumed more control, creating Anglo-Saxon England in the process. The Picts in northern Scotland were outside the applicable area.