They know a lot, but much of it is spun/slanted or falsehoods, thanks to various clergies spotlighting their gods and decrying others, and wild runaway rumors. However, sages trying to be dispassionate can piece together a very good overall picture.
#realmslore
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Isaac
@IsaacBooth19
@TheEdVerse , quick question, how much of the events of the Time of Troubles do the peoples of the Realms actually know? Thinking about sending my 5e players back in time to experience the Realms during the time covered by the Grey Box when I started playing.