Ancient Dragon (古竜; koryuu) is a family that premiered in BS01, being the family of the first X-rare, The DragonEmperor Siegfried. Cards in the family are primarily Red, but could also be spotted in other colors in the form of remakes of the Siegfried, or collaboration.
In the lore, back in Lolo's era, Ancient Dragons refer to those dragons who lived in the Red World before the Dragons (竜人) came, and who lost in the war against the indigenous species, the Terra Dragons. Since most of them are too powerful and gigantic in size to be eliminated, they were sealed in different places and remained dormant until the Vanity Deity invaded. They were worshipped by the Dragons for their power despite their defeat, and eventually awoke from their slumber to face the Vanity Deities.
As the description above implies, the Ancient Dragons are in general high in costs, and a lot of them serve as impactful attackers or finishers. They also commonly serve as the family of the final form of an evolution series, symbolizing the peak of power, or a family of a lord that rules over a place, working similarly as Purple's Evil Deity family in a way. It hence serves as a common family for X-Rare in Red since the early stage of the game. As the "single powerful entity" family for a very long time, however, it also means that the family has very few direct support to the family as a whole. It's not until the Advent era that it receives more direct support.
In the early stage of the game, Ancient Dragons often come with effects like Crush and addition of symbols that showcase their power, with The Deity Catastrophedragon and The BullDragonDeity Dragonic-Taurus being some famous examples. In Heroes era, two of the Red Supreme Hero X-Rares, referencing Yamato Takeru and Susanoo-no-Mikoto, two legendary figure in Japan folklore and mythology, possess such family. Early Ancient Dragon Spirits like The FlameDragon Ma-Gwo are remade into powerful Spirits that brought significant impact to the environment.
In Ultimate era, the family serves more as a support on the Spirit side, and has received their first Ultimates as remakes of the old Ancient Dragon Spirits. On the collaboration side, it becomes a major family for the toho kaijus and ultra kaijus that aren't coming from the space (which are usually Astral Dragons). It is hence also a major family in the Godzilla series. In God-King era, the family is picked up together with the Dragon Emperor family with the The FiveGoodDragonEmperors archetype, and has made itself an all-colored family in the process. Boss Ultimates on the Evil God side like The Hellflame FourDemonLord Bram-Zand are also in the family.
In Advent era, Siegfrieds, the signature Spirits of the family, who then become a legend in Grand-Lolo, have appeared in different continents, and are advented by Alex's escorts or their enemy, the Vanity Deity, in the war revolving around the search of Lolo and collapsing of the world. Unlike the FiveGoodDragonEmperors, single-color non-Red Ancient Dragon Siegfrieds carrying the traits of the various colors are hence born with a number of special keywords. More direct support of the family also appeared as a result.
In Ultra Advent era, the family has finally received their main set Grandwalker: The CreatorGrandwalker Brahma. In lore, it is mentioned that the Ancient Dragons in Grand-Lolo actually came from the Hindida world, and the bloodline is showcased by the "Ma-" tribe cards (e.g. The RishiDragon Ma-Daksha -Humanoid Form-). The "Ma" tribe Ancient Dragons have got both humanoid forms and dragon forms, and are designed to work with each other. It is also revealed that Guren, the main character in Sword Blade era lore, may actually came from a small country of Ancient Dragons, as he is made into a Grandwalker that supports the Ancient Dragons, and the family fits the description of not being one of the 12 major families of Light and Dark in Sword Blade era.
