During the Age of Myth (somewhere during the BCE period), the Dark Dragon emerged allowing the Evil Deities's return to the earth. The Dark Dragon wasted no time and quickly plunged the world into a dark abyss of death and destruction. In this chaos, the evil deities mixed their essences with the bloodlines of the entire human race, creating servants out of the ancient humans, most of whom revered the evil deities as gods. These ancient tribes splintered off, most of which were ruled by the evil deities such as the Lycanthrope Tribe. However one tribe rebelled against their masters and sided with the Heavenly Dragons, they would then be known as the Dragon Lineage.
It was a warrior of the Dragon Lineage who proved himself as the most powerful of mankind, earning the dying Dragon's trust to carry on their duty. His proficient strength, skill and pure spirit allowed him to wield the Dragons' divine weapon, one of their own fangs in which they place all their essence, souls and spirit as they left the mortal realm. Upon receiving this weapon, the warrior's blood was infused with Dragon's blood now coursing through his veins, allowing only him and descendants of his bloodline to wield this weapon, now known as the Dragon Sword. The warrior then used the Dragon Sword to slay the Dark Dragon.
The Dragon Lineage continued their fight against the Evil Deities and their fiendish armies for generations, passing their holy Dragon Sword through the generations as well. Eventually the descendants of the warrior who slew the Dark Dragon would become Dragon Ninja, as the priestesses of this tribe became Dragon Shrine Maidens.
This new Dragon Ninja clan would eventually banish all the Evil Deities to eternal slumber in Hell as the Heavenly Dragons once did before them, and dispersed the ancient tribes, allowing the humans to develop without the influence of their "gods". They would also recover the Dark Dragon Blade and pass down their artefacts throughout the ages, safeguarding them from the forces of evil. With the ancient Dragons long gone, the vigilant Dragon Ninja carried on their duty, guarding the world and mankind from within the shadows, forever at war with the Fiends and their allies.
"Since ancient times, the Dragon Gods and the Evil Deities have fought. the Evil Deities have the power to destroy mankind in an instant. But that power was sealed by those whose veins hold the blood of the Dragon Gods."-Ninja Ryukenden OAV.
- "However, in that age of chaos all of the bloodlines of Ancient tribes were mixed and the form and nature of the Ancients has been carried on by us, the Fiends." -The Book of the Fiends
- "Those of the Dragon Lineage like yourself draw their blood from the same ancient deities.. as the fiends." -Doku, Ninja Gaiden
- "Among the strongest of mankind, Dragons’ blood courses through their veins. Members of this bloodline, the Dragon Lineage, have vowed to stay vigilant and protect our world from the threat of the Archfiends." -Ninja Gaiden II instruction booklet"
- Muramasa: "But she bores the Dragon Sword, How? Only those with Dragon blood in their veins can wield that blade"
Ryu Hayabusa: "They took my blood, and the Dragon Sword" -Ryu and Muramasa cutscene, Day 8, Ninja Gaiden 3
- "The bearer of this divine weapon must possess the physical strength, vigorous spirit, and proficiency of technique necessary to wield it properly." -True Dragon Sword, Ninja Gaiden II
- "The leader of these people has throughout history always carried the legendary Dragon Sword, used to defeat evil wherever it surfaced. It is fate of the Dragon Lineage to be inexorably linked to their nemeses, the Evil Deities." -The Dragon Lineage, Ninja Gaiden Instruction Booklet
- "Impudent apes, how your hubris has grown in the few short millennia we've been away. Have you forgotten the era where only the mercy of the Archfiend kept your lowly species alive? You ungrateful monkeys. When high infernal priest Dagra Dai resurrects and restores the Archfiend to power, you will learn your true place on this earth. On behalf of his lordship Dagra Dai, I deliver you an ultimatum. Submit, or die." -Zedonius, Ninja Gaiden II