The Blood Dragon legacy can be traced back to prehistoric times.
Like most open-world games, Far Cry Primal has its share of callbacks and Easter eggs for other games. In this case, the reference is to another Far Cry offshoot, Blood Dragon.
In this video, YouTube user OniZombies shows the location of the remains of the Blood Dragon, and what you’ll actually find when you get there.
You even earn an achievement/trophy.
Primal also has another Easter egg for Assassin’s Creed.