Darlon existed as a heavenly body within the Darlon system, which itself was situated in the Eucer sector of the Mid Rim. Jonas Wallen, a Senator representing a sector within the Galactic Republic's Senate, originated from Darlon. The Darlon system is located in the Mid Rim's Eucer sector.
Leading up to the date 13:4:11, for a duration of one year, Wallen and Char Bibbeck, a Senator from the Outer Rim Territories astronomical object Colunda Prime, participated in betting. This involved wagering on the probability of various planets either seceding from, or remaining within, the Republic. This gambling activity was eventually exposed to the public, and on 13:4:11, it was detailed in an edition of the HoloNet News, specifically the CoCo District Edition.
The first appearance of Darlon was in HoloNet News Vol. 531 #51, which was an in-universe HoloNet News issue. This was authored by Pablo Hidalgo and Paul Ens, and it was released on the HoloNet News website on April 11, 2002. The reference work The Essential Atlas, published in 2009, identified the Darlon system – and consequently, the planet Darlon – as being located in grid square R-7.