The Elibe Series is an unofficial term referring to a grouping of related Fire Emblem games, namely Fire Emblem: Binding Blade, and Fire Emblem: Rekka no Ken. Both games take place on the continent of Elibe and were released for the Game Boy Advance. However, even though Binding Blade was released almost one and a half years before Rekka no Ken, it serves as a sequel in terms of plot; the events of Binding Blade take place 20 years after Rekka no Ken. Several characters seen as children or otherwise in Rekka no Ken appear older in Binding Blade.
The Elibe Series marked a notable turning point for the Fire Emblem series: the creator and longtime supporter of the series, Shouzou Kaga, left in pursuit of other projects, and the series debuted on a portable console for the first time.
Both games were developed and released for the Game Boy Advance, but Rekka no Ken was the first game in the series to be released outside of Japan (which was simply named Fire Emblem to present the series in other regions). This happened almost exclusively due to the overwhelming popularity of Roy's (along with Marth's) cameo in an earlier released, non-series fighting game, Super Smash Bros. Melee on the Nintendo GameCube. Binding Blade was never released outside of Japan, despite its successor's worldwide popularity, a preclusion that baffled many Fire Emblem fans.
As a result, while the Elibe setting is of somewhat average popularity in Japan, it and its characters, particularly the Rekka no Ken cast, tend to be the favorite of many overseas Fire Emblem fans. It is suspected that, while Roy was in Melee mostly for promotional purposes, Lyn made an appearance as a "battle item" in Super Smash Bros. Brawl, in large part due to that character's overwhelming popularity overseas as well. American-produced fan games, such as Elibian Nights or Immortal Sword, tend to focus on this setting.
While some fans of the series include Fire Emblem: The Sacred Stones (the third of the 3 Game Boy Advance titles) as part of the Elibe Series, no hard evidence has surfaced that would suggest that it is linked by setting to the previous two.