Over the course of eight seasons, only explored certain regions of Westeros, leaving the lingering questions of what the Seven Kingdoms are and why are they called that if there are actually nine of them. Seven Kingdoms make up a huge part of the show and its spinoff series, , despite also exploring regions of Essos as well, Given that this is where and spend the vast majority of their time and that numerous characters refer to "the Seven Kingdoms," it's surprising that the shows never explain this odd little piece of nomenclature.
Finding the genesis of the Seven Kingdoms involves going back to the time of Aegon's Conquest, which happens before 's Targaryen civil war, and around 300 years before the events of . When Aegon Targaryen landed at Blackwater Rush with his sister-wives, Rhaenys and Visenya, it was part of a Westeros that was divided into seven separate realms:
's Seven Kingdoms feature vastly different landscapes and political practices, despite being ruled under one head. The North, led by House Stark, was one of the main locations shown in along with King's Landing but the Tyrell's Highgarden wasn't really seen. However, it was described as a beautiful place filled with flowers. The mountainous Vale had an interesting form of punishment for their prisoners, in the form of a gate on the floor that would force their inmates to fall to their deaths. Dorne is a mixture of desert and tropics, featuring a rather standard-looking prison.
Meanwhile, Casterly Rock was only seen a handful of times in House Tully's Riverlands were featured in several episodes including being the location of the . A stark contrast to these is the Iron Islands, which are dark and stormy, a perfect complement to the dangerous seas surrounding them. The rest of Westeros remained largely unexplored in and season 1 didn't add much more to the context of those other areas.
The Seven Kingdoms were the seven lands that Aegon set out to conquer and unite before , which he mostly did over the course of the next two years, bringing them together under the rule of House Targaryen and the Iron Throne When Aegon was eventually crowned at the Starry Sept in Oldtown, he was proclaimed 'Lord of the Seven Kingdoms,' although it wasn't entirely true even then. The Dornish resisted Aegon's attempts to conquer them by hiding out in the Mountains and engaging in guerilla warfare, and Princess Meria refused to yield.
It wasn't until that Dorne officially joined the Seven Kingdoms thanks to a peaceful marriage pact between Dorne's leader at the time, Prince Maron Martell and the younger sister of King Daeron II Targaryen, Princess Daenerys Targaryen (not to be confused with the central character on ), thus finally making the realm whole. However, this was actually turning ' Seven Kingdoms into nine, because Aegon had long since made some big changes to his newfound empire.
The Riverlands, which had long ago been independent, were ruled by House Hoare during Aegon's Conquest. However, as a reward for supporting the Targaryens against the Hoares, the Kingdom of Rivers & Isles was split into two: House Tully was granted lordship over the Riverlands. At the same time, House Greyjoy assumed control of the Iron Islands. That made it into Eight Kingdoms, while Aegon Targaryen also decided to make King's Landing and the surrounding area into a principality of its own, known as the Crownlands, which was loyal solely to the crown.
Because of their service during the Conquest, command of the Reach passed to House Tyrell, while House Baratheon was granted the Stormlands. Therefore, should feature all nine kingdoms at some point, considering it takes place at the beginning of the end of the Targaryen reign and the book includes the majority of them.
So, the Seven (or nine) official Kingdoms of and are made up as follows:
If that looks familiar, it's because it's a status quo that existed from the events of . At this point, the Baratheons took the crown, and then further changes were made following ' War of the Five Kings. The Seven Kingdoms as people know them were established with Aegon's conquest, or when Dorne officially joined and remained so throughout the entire run of until the finale.
The prequel series has branched out its filming locations, which allowed the in-story world to expand. The TV show kicked off with the seeds being planted for the Targaryen civil war, so most of the series focused on King's Landing. The show also included several characters from places like Oldtown and Dorne but they haven't been a significant part of the series thus far. However, did expand to show the Steptones and even Storm's End.
Based on the book the story is adapted from, even more places can be explored in . For example, Jacaerys Velaryon visits Winterfell, though that has been seen a lot in . There's also the chance for further looks at the Reach, the Iron Islands, the Vale, and more given the places that characters visit in the books and who gets involved in the "Dance of the Dragons."
While the rest of the Seven Kingdoms and the history behind the name has not been addressed in the existing series, it might be something that could be addressed in some of the spinoffs. In terms of the type of spinoff surrounding this part of the history, a series on Aegon's Conquest would be a thrilling story to tell and is a popular idea for a spinoff among fans, especially given the revelation about . The series has not yet been announced, but even if it was, it is unlikely it would fully answer the question of the nine realms as that concluded long after Aegon's reign ended.
It doesn't seem likely the story of Dorne joining the Seven Kingdoms would be exciting enough to explore in a spinoff as that period of time in Westeros was not as notable. However, the best way to give the answer to the truth behind the Seven Kingdoms is by having a character give a brief history lesson. Throughout , there were instances of characters ruminating on past events, including Shireen Baratheon discussing the Dance of the Dragons and Tyrion discussing the Doom of Valyria with Jorah Mormont. Such moments add to the world-building of the franchise and could be used to answer the lingering question of the nine realms inside the Seven Kingdoms.