Aegon IV/Theories

From A Wiki of Ice and Fire

Martin says that Viserys II was in his fifties when he came to the throne. That sets his birthyear before 122 AL but not much because his older brother was still a boy in the period 129-131 AL

And Baelor Breakspear, Visery's great-grandson was born in 169 (having died in 208 when he was 39). That means that Daeron, Baelor's father must have been born before 154 and Aegon IV then before 139. (Let's say that someone must be 15 to father a child). And Aegon cannot have been born much earlier because Martin says that he was young when he began his realm

139 AL, or a few years before is also suitable because it makes it possible that his younger brother, Aemon, was old enough to participate in the Conquest of Dorne (157-161)