Monmouthshire
The Marcher Lordships were the basic units of administration for the next 450 or so years, until Henry VIII passed the Laws in Wales Act 1535. This Act abolished the Marcher Lordships and established the County of Monmouthshire, combining the Lordships east of the Usk with Newport (Gwynllŵg or Wentloog) and Caerleon to the west of it.
Read more about this topic: Kingdom Of Gwent