The Dream Cycle refers to a series of stories by author H. P. Lovecraft

H. P. Lovecraft

Howard Phillips Lovecraft --often credited as H.P. Lovecraft — was an American author of horror, fantasy and science fiction, especially the subgenre known as weird fiction....

. These stories concern themselves with "The Dreamlands": a vast, alternate dimension

Parallel universe (fiction)

A parallel universe or alternative reality is a hypothetical self-contained separate reality coexisting with one's own. A specific group of parallel universes is called a "multiverse", although this term can also be used to describe the possible parallel universes that constitute reality...

 that can be entered via dreams.

Geography

The Dreamlands is apparently divided into four regions:

• the "West" (location of Steps of Deeper Slumber, the port of Dylath-Leen
  Dylath-Leen
  Dylath-Leen is a fictional city in H. P. Lovecraft's Dream Cycle and appears in The Dream-Quest of Unknown Kadath and the Brian Lumley short story Dylath-Leen....
  
   (largest city of the Dreamlands), the town of Ulthar
  Ulthar
  Ulthar is both a fictional town and a fictional deity. The town of Ulthar is part of H. P. Lovecraft's Dream Cycle, appearing in such stories as The Dream-Quest of Unknown Kadath , "The Cats of Ulthar" and "The Other Gods" .-Town:...
  
   (where no man may kill a cat), Hlanith (a coastal jungle city), Ilarnek (a desert trade capital), Mnar, the ruins of Sarnath
  The Doom that Came to Sarnath
  "The Doom that Came to Sarnath" is an early short story by H. P. Lovecraft. It is written in a mythic/fairy tale style and is associated with his Dream Cycle...
  
   and Enchanted Wood);
• the "South" (location of the isle of Oriab
  Oriab
  Oriab is a fictional location in H. P. Lovecraft's Dreamlands. It is a large island in the Southern Sea and is lush and fertile. Its most prominent landmark is the tall, snow-capped mountain Ngranek. It is home to the magah birds that nest in its resin trees.- Baharna :Baharna is a major seaport...
  
   and the Fantastic Realms);
• the "East" is (location of the city Celephaïs
  Celephaïs
  "Celephaïs" is a fantasy story by American horror fiction writer H. P. Lovecraft, written in early November 1920 and first published in the May 1922 issue of the Rainbow.The title refers to a fictional city that later appears in H. P...
  
  , created from cloth by its monarch King Kuranes
  Kuranes
  Kuranes is a fictional character in H. P. Lovecraft's Dream Cycle. He was introduced in the short story "Celephaïs" and also appeared in The Dream-Quest of Unknown Kadath ....
  
  , the greatest of all recorded dreamers, and The Forbidden Lands);
• and "the North" (location of the Plateau of Leng
  Leng
  Leng is a fictional cold arid plateau in the Cthulhu Mythos, whose location seems to vary entirely from story to story. The Plateau of Tsang, referenced by H. P...
  
  , complete with man-eating spiders and satyr
  Satyr
  In Greek mythology, satyrs are a troop of male companions of Pan and Dionysus — "satyresses" were a late invention of poets — that roamed the woods and mountains. In myths they are often associated with pipe-playing....
  
  -like beings known as the "Men of Leng").

Other locales include "The Underworld" (a subterranean region underneath the Dreamlands and inhabited by monsters), the "Moon

Moon

The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

" (accessible via a ship and inhabited by "moon-beasts", creatures allied with Nyarlathotep

Nyarlathotep

Nyarlathotep, also known as the Crawling Chaos, is a malign deity in the Cthulhu Mythos fictional universe created by H. P. Lovecraft. First appearing in Lovecraft's 1920 prose poem of the same name, he was later mentioned in other works by Lovecraft and by other writers and in the tabletop...

) and Kadath, a huge castle atop a mountain and the domain of the "Great Ones".