Denobula was a planet located in the space of the galaxy's Alpha Quadrant, a class M planet located in orbit of the Denobula Triaxa star system, homeworld to the Denobulan civilization.
There is just a single large continent on Denobula which by the mid-22nd century contained a population of approximately 12 billion inhabitants. (ENT episode: "The Catwalk")
In 2158, a Romulan force led by Admiral Mindar boarded a spaceport orbiting the planet, having everyone aboard murdered. He then ordered the Denobulan people not to interfere at which point Mindar ordered an attack on the planet from his fleet of ten Romulan battle cruisers. Three million Denobulans on the planet's surface were killed. (ST reference: Federation: The First 150 Years)
In the mid-23rd century, the national reserve bank in the capital city was broken into. The thief or thieves stole nearly three hundred million credits' worth of ancient gemstones. The crime was unsolved by August 2267, but Lieutenant Haniff Jackson of Starbase 47-Vanguard suspected one Joshua Kane as the culprit. (VAN novel: Precipice)