From A Wiki of Ice and Fire
|Title|| Lord of Casterly Rock|
Warden of the West
Lord of the Westerlands
|Book(s)|| The Rogue Prince (Mentioned)|
The Princess and the Queen (Mentioned)
During the civil war known as the Dance of the Dragons (129-131 AC) he was loyal to King Aegon and the greens against Rhaenyra's claim. At the end of the conflict Jason Lannister was dead and left Casterly Rock in considerable disarray. Lord Jason's brother Tyland was the master of coin during the Dance of the Dragons.