Post-FotJ, Pre-Legacy Speculation
There's about a 85 year gap of information concerning galactic affairs (45 ABY to 130 ABY).
Luke Skywalker died somewhere along that time period, perhaps protecting Allana from the One Sith.
After Skywalker, it seemed Allana Solo took the throne as ruler of the Jedi and the entire galaxy.
Solo's career, based on visions by Caedus and Luke, seemed to mark an unprecedented golden age of peace.
Like Revan postponed Vitiate's invasion, I imagine Allana postponed the One Sith's.
I figure Allana passed away sometime near 130 ABY, and then the One Sith invaded shortly thereafter.