Analysis of information sources in references of the Wikipedia article "冰與火之歌的世界" in Chinese language version.
The 7 kingdoms usage of course dates from the time of Aegon the conqueror. At that time, there was the King in the North[錨點失效] (1), the King of Mountain and Vale[錨點失效] (2), the King of the Rock[錨點失效] (3), the King of the Reach[錨點失效] (4), the Storm[錨點失效] King (5), the King of the Iron Islands[錨點失效], who also ruled the riverlands[錨點失效] (6), and the kingdom of Dorne[錨點失效], which was ruled by a prince (7).
The 7 kingdoms usage of course dates from the time of Aegon the conqueror. At that time, there was the King in the North[錨點失效] (1), the King of Mountain and Vale[錨點失效] (2), the King of the Rock[錨點失效] (3), the King of the Reach[錨點失效] (4), the Storm[錨點失效] King (5), the King of the Iron Islands[錨點失效], who also ruled the riverlands[錨點失效] (6), and the kingdom of Dorne[錨點失效], which was ruled by a prince (7).