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That assassin that Arya frees seems to be invincible and says he can slay anyone. (I don't know how he was captured in the first place.) Arya is learning that same assassin art. The red priests all seem invincible. All the merchants of Essos seem to have much more wealth. The Iron Bank on Essos. The Targaryans actually came from across the sea with dragons and took over. Plus only Westeros lives in the shadow of the threat from the Others. Is there any explanation about why Westeros isn't just a vassal land to Essos?

marked as duplicate by Möoz, Ward, Often Right, Valorum Mar 23 '15 at 8:12

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  1. The cities of Myr, Tyrosh and Lys are too busy fighting over the Disputed Lands to invade.
  2. Other cities need to focus on defending themselves from the Dothraki.
  3. Braavos was founded on the principle of freeing slaves - turning Westeros into a vassal state doesn't sound like something they'd do.
  4. That said they do, through the Iron Bank, already have huge influence in Westeros economically. When the crown stopped paying back their debt to the Bank, the Bank started supporting Stannis to take control, so they are getting even more involved in recent times.
  5. The Faceless Men of Braavos believe they are serving their god, not the desires of men. The cost to hire them depends on the target and the client. To use them to conquer an entire continent would be inconceivably too expensive.
  6. Many of the free cities, such as Pentos and Volantis, appear to have too much internal political instability to be capable of invading another continent.
  7. The people of Qarth are too busy basking in their own glory to even consider doing something like thinking about smelly Westeros.
  8. It would take a lot of ships to transport enough men across the sea, and before they could land they would need to defeat the navies of Westeros.
  9. And finally, we don't actually know the populations of the cities in Essos. Many of them have large slave populations, but we don't know how many could field armies that would rival those of Westeros. Renly had a hundred thousand men. The 8000 Unsullied that Daenerys freed are surely worth many times that compared to the peasant farmers of Westeros, but how many? Would it be worth the risk to fight even just the 6000 Gold Cloaks of King's Landing?

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