Which fictional realm does J.R.R. Tolkien’s The Hobbit mainly take place in?

J.R.R. Tolkien’s The Hobbit mainly takes place in Middle-earth. Middle-earth is the central region of Tolkien’s imagined world during the events of The Hobbit and The Lord of the Rings, containing the Shire, Rivendell, Mirkwood, Lake-town, and the Lonely Mountain.

Bilbo’s journey begins in the Shire and moves eastward through lands inhabited by Elves, Goblins, Men, and the dragon Smaug. The term Middle-earth is Tolkien’s rendering of an old Germanic and English concept for the inhabited world, rather than the name of a single country or political kingdom.

Valinor and Aman are associated with the Undying Lands west of Middle-earth. Númenor is an island kingdom that existed mainly in the Second Age and was destroyed before the main Hobbit-era story. These locations belong to Tolkien’s wider legendarium, but they are not the primary setting of Bilbo’s adventure.