A "thieves' guild" is the colloquial name in the Old World for the organised crime syndicates that dominate the underworlds of many of the continent's cities and towns in the Empire, Bretonnia, Kislev and the southern realms of Estalia, Tilea and the Border Princes.[1a]
Thieves of the Old World belong to the illegal syndicates known as thieves' guilds. They have little choice -- the guilds are much better at finding thieves than the local watch, and insist that all active criminals take advantage of the benefits of membership.[1a]
If a city has more than one guild, both normally insist that every thief join them, and not the other. This leads to gang warfare, so in a few cities two guilds ignore each others' existence. Thieves in the city must belong to both, but pretend not to know about the other guild. The masters of one guild are low-ranking members of the other, and are generally left alone. Thieves have to pay two sets of dues, and may be given tasks by both guilds at once, making it difficult for them to avoid offending someone.[1a]
In a few cases the guild has become rich through ownership of respectable businesses, and has a great deal of influence with the legitimate government of the town or city. Indeed, a handful of towns are actually run by their thieves' guild, in which case the watch is only concerned with unlicensed criminality. Normally, such towns collapse into anarchy, as the guild allows too much crime to maintain stability or a functioning economy, but in a few cases the leadership actually imposes stability and a reasonable level of lawbreaking. This often leads to a splinter guild forming, to protect the rights of dishonest thieving folk.[1a]
Travelling thieves have to come to an arrangement with every guild they meet. Sometimes this is easy, if the guild requires nothing but a percentage of their take. Others, the majority, impose significant ordeals on potential members, and taking one of those trials every couple of weeks is bad for the health. Travelling thieves thus often try to avoid the notice of the local thieves' guild as well as the watch.[1a]