The Far Reaches was the domain of the corrupt and greedy Grim Tuesday, one of the main antagonists of The Keys to the Kingdom series. It was also the second demesne that Arthur gained control of as the Rightful Heir.
Originally, the Far Reaches was a Grand Cavern, and in the cavern was a steady spring of Nothing. Tuesday used the Nothing to create items, such as Commissionaires and Not-Horses, which he sold to other demesnes of the House. His avarice, however, drove him to deepen and widen the spring in an effort to find more Nothing. In time, the spring became a vast Pit, which eventually becomes the whole of his demesne, sparing only his Treasure Pyramid and the train station where his personal train arrives into the Pit docks.
Grim Tuesday used indentured slaves from his own demesne, as well as ones from other Morrow Days sent to him as payment, to mine the useful amounts of Nothing. The pit is extremely dangerous as it has been dug deep into the foundations of the House and is very close to breaching into the void of Nothing beyond. After Grim Tuesday was deposed, Dame Primus received regency over the Far Reaches and ordered their Denizens to fill the Pit, but was unable to have this task completed before the Far Reaches were destroyed by a wave of Nothing released by Superior Saturday. The entire demesne was consumed by the wave of Nothing in 4 to 5 minutes. The Immaterial dam wall was breached by sorcerous drills. During the interim before this event, many of the things produced by Grim Tuesday for the other demesnes had become scarce as a result of the cessation of production caused by Dame Primus' orders.
After the horror was over, the New Architect is highly assumed to have the Far Reaches rebuild to the time before Tuesday gone corrupt and placed it under his control.