From the artist:
 
THE PRINCIPALITY OF CANTERLOT
 
Canterlot is the personal domain of the sun empress, governed by royal agents distinct from of the imperial government of Equestria. It extends from the grant city itself to the far edge of the Everfree, and to the western bank of the Dneighper river and great Whitetail Wood. Its core lands are the Dneighper Valley and the expansive but tranquil forests, all north of the now defunct Principality of Everfree and the jungle which has annexed it.  
Canterlot is the grandest of the unicorn mountain cities, the shining jewel of Central Equestria. Originally the seat of House Blackhorn, Celestia I was invited to rule by the city’s nobles after Argo Blackhorn the Reckless died in battle leaving no ‘worthy’ heirs. For several hundred years, the Blackhorn cadet houses sought to retake their city, but each time were put down by the new Empress. Now Canterlot’s greatest threat is from within, as the urban nobility grows ever bolder and more ambitious.  
The lands just under Canterlot are a thin band of gentle hills and fertile riverbanks known as the Canter. Providing barely half of the food for the imperial city above them, the ponies of the Canter have long suffered as indentured serfs to the petty urban nobles therein. The burden of containing unrest has always fallen to agents of the princess who, while sympathetic with the commoner cause, would not suffer having their empress face revolt so close to home.  
The forests of the Principality of Canterlot (sometimes called the princess-pality by the commoners), are vast and largely anarchic, lacking roads or ties to the central authority of Canterlot City. Hundreds of tiny villages hide in the shade of the trees, their stout ponies living a life in blissful ignorance of politics and taxes. Wild creatures may roam in the deepest hollows, but only under cover of night do they prey, and the hardy villagers never go without a fight.  
The Griffinbend, situated on the opposite side of the Dneighper Valley from Canterlot, is home to the largest population of non-ponies in Equestria. Originally a fief of house Blackhorn, the small barony of Embankment was granted to a Kestrelian griffin mercenary lord by Celestia I upon her accession to the Canterlot throne. Renamed to Uferböschung, the castle became the seat of the new house Scharffeder, and has since attracted any and all equestrian griffins who would find the institutionalized discrimination under other lords intolerable.  
The Free City of Ponyville sits on the southern border of the principality, where it holds a commanding presence on river trade between Canterlot and the breadbasket of the Dneighper Run. The smallest of the free cities by far, Ponyville was paradoxically one of the first chartered cities to receive such an honor, with the act of liberation dating some hundreds of years before the city’s supposed founding. Still, the riverside hamlet been the archetype of quiet pastoral life in Equestria, and as long as peace continues to reign in the empire that shouldn’t change.  
And lastly there is the Everfree Forest, a name spoken in hushed tones and only with great reluctance. Once the land where the forest now grows was the prosperous Principality of the Everfree, founded by Celestia I and her sister. However the scourge of the Great Corruptions to the north and the Wars of Unification in the riverpony lands depleted the population greatly, as Celestia tried and failed to play the great game on the level of the other lords. The rebellion of Celestia’s sister and the resulting War of the Nightmare Pretender sealed the fate of the fledgeling state. Twisted trees and hateful brambles are all that grow there now, and fell beasts haunt the graves of heroes and monsters alike.  
Well there you go. It’s a map. I hope you’ve survived this dose of my personal headcannon expanded-universe, and found it at least somewhat interesting. There’s more to come, I think.