The Guild Union (ユニオン誓約 Yunion Seiyaku?, "Union Oath") is a congregational association settled in Dahngrest that thoroughly operates as the leading source of power for guilds in Tales of Vesperia. The Union's headquarters are located in the northern area of Dahngrest, and their authority is dictated through the guild-based influence of the city, as well as through the representation of the Five Master Guilds, the five most powerful guilds in the Union. Approximately ninety-percent of all guilds are part of the Union.