Prydain

Great Britain and adjacent islands in the 5th century AD, before the invasion and subsequent founding of Anglo-Saxon kingdoms.
  Mainly (non-Pictish) Brittonic areas
  Mainly Pictish areas
  Mainly Goidelic areas

Prydain ([ˈprədai̯n], PRUH-dine; Middle Welsh: Prydein) is the modern Welsh name for Great Britain.