There have been a lot of questions about the Seers and their ancient war with the mursaat. Sadly, these aren’t questions we can answer at great length without giving away some
very deep secrets of the Guild Wars world. I can say that they are one of the oldest races of Tyria, dating back long before the Gods brought the humans to the world; to the time of the writing of the Tome of Rubicon. In those ancient days, the Seers fought against the mursaat, but they were in turn defeated by their enemies, and their civilization lost to the ravages of time.
Some remnants of that civilization, and that ancient time, still remain in modern-day Tyria (
both in GW and
GW2), but often, those who discover such things do not realize what they have found.
There are opportunities in Guild Wars 2 to uncover some of the most ancient lore, including previously untold tidbits about the Seers and their story, but such information will be very difficult to come by.