@TheEdVerse Aside from drow sign language, are there any sign languages that are commonly known across many regions of Faerun?
— sno4wy (@sno4wy) May 3, 2020
Yes. As per official D&D, illusionists share a silent sign language, as do thieves. Alignment tongues include a few gestures.
The Harpers also have ‘silent signs,’ as do the Zhentarim. And the Red Wizards. And the Lords Alliance. And quite a few cabals and guilds. Wait——alignment tongues? I thought they are from the "basic" D&D rules and not included in the Realms, which is a AD&D setting?
— 子虚子 (@crabgao) May 5, 2020
The Realms predates D&D, but yes, became an AD&D setting.
AD&D Players Handbook p.34: "In addition to the common tongue, all intelligent creatures able to converse in speech use special languages particular to their alignment. These alignment languages are…" etc.#Realmslore
— Ed Greenwood (@TheEdVerse) May 5, 2020
In researching the Avariel for a new character, I found one website that said they had their own sign language, as well. Is that accurate? Yes, but note that it's largely a silent language of aerial movement (wing dips, stalls, flaps), MOST of it not as subtle as non-flying races' sign languages. It's primarily meant for communication in flight.#Realmslore
— Ed Greenwood (@TheEdVerse) May 13, 2020