Thrones are the physical "seat of power" of a kingdom.
“The Crystal Throne is the seat of power of the Seanchan Empire, located in the Court of the Nine...Crystal Throne
“The Throne of the Clouds is the seat of power in Kandor, located in Chachin's Aesdaishar Palace...Throne of the Clouds
“The Throne of the Winds is the seat of power in Altara, located in Ebou Dar's Tarasin Palace. ↑...Throne of the Winds