The country claims to have its roots roughly 6,000 years in the past, which may not be eternal but is close enough to qualify. The ruler of Calanfer sits on the Eternal Throne of Calanfer, and Lyonette du Marquin, sixth princess in line to that throne, has been seen to also use that attribute in swearing.
The kingdom of Calanfer does not lack for [Princesses] and [Princes], but is not notably powerful militarily or economically. Their main capital are their royal heirs who can make political marriages and thus safeguard the kingdom through diplomacy.
Due to the Terandrian policy of ichorial lineage where pureblood nobility carries enormous political weight, Calanfer can be suspected to be rather influential despite not being powerful.
- Note: As history nerds from Earth will point out: the (allegedly) longest-reigning dynasty on Earth was that of Imperial Japan, and even their long rule of roughly 2000 years was neither continuous nor undisputed. Millenia-lasting countries on Earth, most prominently Ancient Egypt with a history of roughly 3000 years, had way over 30 dynasties succeeding each other. So far, the story has not elaborated on the age of current House Marquin's bloodline; but it would be likely that within the Kingdom, not much besides the Throne itself and the Name Calanfer are actually 6000 years old.
- Note also: Very powerful magical means could stabilize a nation against the inheritance disputes mentioned above, also against civil strife or unrightful usurpation. Some institution might shield Calanfer against major changes: long-term stabilizing factors are used in the Reinhart family, in Khelt and in Germina, for example.