Yes, this has been asked multiple times by different people. Sometimes, I think popular questions like these should be turned into a single, sticky thread, to make it easier for newcomers to find them.
First of all, for the most comprehensive look at the story prior to ARR, look here:
The Rise and Fall of the White Raven.
The video version is here:
http://youtu.be/TXc0loyuq9I
Second, there is a thread somewhere, in which
Enkidoh explained how the original plot line ended very abruptly shortly after the Circle of Knowing (comprising the Archons Y'shtola, Thancred, Papalymo and Yda) confronted Nael van Darnus for the first time. But I can't find it now. The gist of it was that the player-character was one of many individuals blessed (or cursed, depending on whose perspective you use) with the Echo. The Archons gradually directed these individuals to the Path of the Twelve, a secret quasi-religious organisation founded by Minfilia. The hope was that these individuals will learn more about the nature and meaning of their gift through their adventures or personal endeavours.
The return of the primals and the impending return of the Empire, changed everything, but... the storyline never got properly resolved. Yoshi-P took over, and the Dalamud storyline, coupled with the introduction of specialised Jobs became the new main story.