Are there any books I can use to learn about the situation of Westeros right after Aegon's conquest? I am looking for things such as lore supplements or game books.
The World of Ice and Fire - The Targaryen Kings: Aegon I
While The World of Ice and Fire is a book about the entire history of Westeros, a large portion of it based on Aegon's Conquest and the Targaryen Kings. Since this takes place before the TV show, the histories are almost certainly 100% accurate to the Game of Thrones canon, even if the show has a slightly different canon.
Parts II - IV are titled the following:
- The Reign of the Dragons, telling about Aegon's Conquest
- The Targaryen Kings, about the reigns of all Targaryen kings, beginning with King Aegon I Targaryen and ending with the reign of King Aerys II Targaryen
- The Fall of the Dragons, about the year of the false spring, Robert's Rebellion, and its aftermath.
You would most likely be interested in the first two/three chapters of the part titled "The Targaryen Kings". This is about the events directly after the conquest during the Reign of Aegon I, Aenys I and Maegor I
- Aegon I Targaryen - The first King of Westeros and the telling of the time straight after his coronation
- Aenys I Targaryen - Aegon I's heir, and the second King of Westeros. This gives us a little more insight into his life and the rule between the years 37 and 42 AC.
- Maegor I Targaryen - Known commonly as "The Cruel" the rise of Maegor to the crown is an interesting tail and the differences in leading the people is an interesting read in it's own right.
Note that because the show uses a different scale of the years (After Landing as opposed to After Conquest) the years might not match up by a value of 2, (if something took place in 1 AC it's probably something like -1 AL) but over the 281 year rule of the Targayens, 2 years doesn't make much difference.
Game of Thrones: "Ultimate Guide" - Histories: Westeros through the ages.
The most canonical resource to the TV shows is the HBO run website www.gameofthrones.com. However the histories provided on the site are very limited, they are really no more than a quick summary of what's provided in the books above.
It is not a book, but if you are interested in the show's perspective you can watch the "Histories and Lore" as part of the each season's release on Blu-ray.
Specific features to watch would be (both from Season 1):
- "The Field of Fire": Viserys Targaryen and Robb Stark give separate accounts of the War of Conquest and the consequences of the Field of Fire.
- "House Targaryen": Viserys Targaryen narrates the origins of the Targaryen dynasty, the conquest of the Seven Kingdoms and the exile of himself and Princess Daenerys Targaryen.
In addition Season 7 features "Conquest & Rebellion: An Animated History of the Seven Kingdoms". This feature focuses more on Aegon's conquest divided into 10 chapters.
The down side is they are only available on the Blu-ray editions and not on HBOGO. I have seen some of the features floating around on Youtube, but I can not speak to their accuracy or legality.