The Allthing, also kown as Grand Gather, is a meeting of all the local Gangrel in a given region.
A Great Gather relies on a powerful Gangrel who is respected by most of the clan to be called, therefore they are extremely rare. When one is called, any member of the clan who can must travel to the meeting place.
Once begun, these gathers usually involve the rites demonstrating status to decide on leadership for the meeting. The rites can take days to accomplish, and must be redone for every Gather, as no two will have the same Gangrel meeting under the same circumstances. Once the hierarchy for the Gather is established, the business at hand can be dealt with.
In the case of an Allthing, similar rites of strength and status that are found in a regular "Thing" also kown as Gather, take place; however, there are no time limits to either the rites or the Great Gather.