Loompaland is the place where the Oompa-Loompas come from.
According to Willy Wonka himself, the whole place is nothing but thick jungles, desolate wastes and the most horrid beasts in the world: Hornsnozzlers, Snozzwangers and Whangdoodles (beasts that, unfortunately, were never documented).
The island itself isn't documented either, not even on a map or computer system, and as a result most people outside of Mr. Wonka's circles dismiss it as nonsense — such as, for example, Mrs. Teavee, who was a geography teacher.
The Oompa-Loompas used to live in tree houses to escape the monsters, where they ate green caterpillars, which, also according to Mr. Wonka, tasted revolting. Mr. Wonka also learned that the Oompa-Loompas craved cocoa beans, which were difficult to find in Loompaland, and so he invited them to work and live in his chocolate factory, where they could have all the cocoa beans they wanted.