It’s called the “Seven Kingdoms” because that name comes from an older political setup in Westeros, even though by the time of Game of Thrones there are actually nine regions.

Origin of the name “Seven Kingdoms”

Originally, before Aegon the Conqueror showed up, Westeros was divided into seven independent kingdoms , each ruled by its own monarch. Those original seven were:

  1. The North
  1. The Vale
  1. The Westerlands (the Rock)
  1. The Reach
  1. The Stormlands
  1. Dorne
  1. The Kingdom of the Isles and the Rivers (Iron Islands + Riverlands together)

When Aegon conquered them, he took the title “Lord of the Seven Kingdoms” , and that title (and nickname for the realm) stuck. Seven is also a sacred number to the Faith of the Seven, which gives the title extra religious weight.

How it became nine

After the conquest, the political map was reshuffled:

  • The old “Isles and Rivers” kingdom was split into two regions :
    • The Iron Islands
* The Riverlands
  • Later, the Targaryens carved land out around King’s Landing to create a new region, the Crownlands.
  • Dorne joined the realm much later by marriage, not conquest, but still became one of the main regions under the Iron Throne.

So by the era of the main series, there are nine regions usually listed like this:

Region| Most famous ruling House
---|---
The North| Stark2510
The Vale| Arryn2510
The Westerlands| Lannister2510
The Riverlands| Tully2510
The Iron Islands| Greyjoy2510
The Reach| Tyrell125
The Stormlands| Baratheon2510
The Crownlands| Targaryen (historically)12410
Dorne| Martell24510

Yet people still casually call the whole thing “the Seven Kingdoms” because of tradition and that old royal title.

The in‑story “gotcha” joke

In the recent discussion around A Knight of the Seven Kingdoms , there’s a fun moment where Egg points out there are nine kingdoms now, which pokes at this exact inconsistency. The explanation characters give matches the lore: the phrase “Seven Kingdoms” is just an old name that no longer lines up with the current map, but everyone keeps using it anyway.

So TL;DR: It’s called the Seven Kingdoms because that was the original constellation of realms Aegon conquered, and the name stuck, even after borders changed and it effectively became nine regions.

Information gathered from public forums or data available on the internet and portrayed here.