The Oradea League is an alliance of a dozen Old Clan Tzimisce elders that refused to bow down before the Sabbat. They maintain their own feudal lands around the Romanian city of Oradea, much like they did during the Dark Ages. Aside from that, the League is quite influential in Russia, which serves as refuge to an unknown number of Old Clan Tzimisce, possibly more than the Romanian dozen. Each Tzimisce within the League is extremly powerful, and most have survived the Anarch Revolt.
The League was - and still is - based on a set of absolute rules, designed exclusively to protect the unlives of the founders. Thus, siring is prohibited unless all founders give it official clearance. A large portion of the Transylvanian Alps has been divided into several domains to fit the needs of the founders. All of these ancient vampires abide strictly by the tradition of Hospitality.
Last but not least, all members of the League have pledged unity against any individual threat from the outside world, be it Lupine or Vampire of either sect. After the first century of its existence, such collective action was seldom needed: the outside world seemed to have forgotten the Old Clan, and the reverse seemed to be true as well. However, after the fall of the Shadow Curtain, aggression from the Shadow Lords escalated and the League became more territorial and protective about their domains.
Clanbook: Tzimisce Revised, p. 19, 29-30, 47-48, 65