In the Middle Ages, the area between England and Wales wherein Marcher lords had some degree of autonomy. It's definition today is somewhat looser, and refers to the area along the English border with Wales.
Fact of the Day
The Tudor Privy Council would sometimes punish those who fell out of its favour by making them wait to be seen by the Star Chamber for days, weeks, or months in London, during which time they would run up huge lodging bills. Wolsey made De Carteret of Guernsey wait for over four years.