Thieves Guild Creation

[Frogmander]

Having troubles finding anything on this..When was the Thieves Guild first started? Is it even known..? Sorry if it's somewhere obvious and I'm just being blind XD

[The SheoDovah]

Which one? The Vvanderfell,Daggerfall, Cyrodiil or Skyrim one? As the Thieves Guild is not one thing in Tamriel. As most provinces have their own thieves guild. The one in Cyrodiil has no contact and so far has no relationship with the Morrowind or Skyrim ones and vice versa.

[Minor Edits]

There are no direct sources on this. Some accounts suggest the Dark Brotherhood is an offshoot of the Thieves Guild, and the Dark Brotherhood's formation predates 2E 358, so the Thieves Guild is a pretty ancient institution in some parts of Tamriel (though it's relatively new in some places, notably Morrowind).

[Marelo]

There appear to be many different guilds, some on friendlier terms than others. At least one member of Skyrim's had to leave his home province and joined up on the strength of prior contact with Brynjolf, for example. And then you have Linwe's merry band, and we know how that turns out.

It doesn't appear that there is a singular body known as the Thieves Guild. I'd wager that the ones known as such simply haven't bothered to give themselves a name. They're just guilds of thieves.