Forking is one of the earliest traditions of Wikipedia

It is news to many people, but Wikipedia has been forking from the very beginning. One of the earliest forks, and a reasonably successful one at that, is the Enciclopedia Libre Universal. The ELU forked from a Spanish Wikipedia in early 2002, about a year after Wikipedia's official launch, and while people on both side of the chasm have been occasionally raising the discussion about merging, it has so far remained only an object of discussion.

It might be illuminating that Wikipedia's related article, [[Enciclopedia_Libre_Universal_en_EspaƱol]], mentions as the first factor that "may contribute to a merger" the creation of Wikimedia Foundation. This event happened years ago in the middle of 2003 and, interestingly, may have been prodded by ELU's split as can be seen from an old speculative list post and Mister Wales' followup confirmation.