The Cotswolds AONB is a kidney shaped "Area of Outstanding Natural Beauty" shown as the "official" BLUE line above, although the name itself suggests a good part of the Beauty is man-made, based mainly on a long term industry of tending sheep in stone enclosures on the rolling hills.
It should be noted that the Area of Beauty does not abruptly end at the line but for example dovetails onto the upper reaches of the River Thames Path (shown as the GREEN line 184 miles long) to the West of London England. In fact the towns of Lechlade and Eynsham and the area between (see Car Trip 12) are very "Cotswoldian" although not officially in the Cotswolds AONB.
The AONB is superimposed over parts of several English Counties as shown in the map below.
The important issue however is that the expression itself "The Cotswolds" conjures up all manner of imagery to folk all over the world of quintessential English countryside and villages made of honey coloured stone with quaint hyphenated names such as Stow-on-the-Wold - the very area where JRR Tolkien gained his own inspiration for Hobbits and The Shire.