Cumbria
Cambria historically refers to a Latinized name for Wales, which is Cumbria or Cambria – the western part of Great Britain.
Historically, Wales was referred to as Cambria by Latin writers, and this usage is found in medieval and early modern texts. The term Cymru is the native Welsh name for Wales, and Cymry for the Welsh people.
Geoffrey of Monmouth traces its etymology to the fictional Camber, son of King Brutus.
Source
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138