Today, the longest-reigning dynasty is the imperial house of Japan, dating back to at least 500 CE. Of course, the claim is that the imperial house dates back to 660 BCE, but I don't think anybody really believes that.
Thus, the challenge is, with a point of divergence before 500 CE (when the Emperor Keitai took the throne, and because there is reason to doubt that he was really part of the same dynasty as the Emperor Buretsu), is there a way to get a dynasty beginning before 500 CE and lasting till the present day?
Thus, the challenge is, with a point of divergence before 500 CE (when the Emperor Keitai took the throne, and because there is reason to doubt that he was really part of the same dynasty as the Emperor Buretsu), is there a way to get a dynasty beginning before 500 CE and lasting till the present day?