4 ideas
After the Buddha's death, King Ajatasattu sealed the relics in an underground chamber guarded by spirit-driven mechanical warriors (bhuta vahana yanta), which went on to protect it for roughly two centuries. When Emperor Ashoka found the chamber, he could not take the relics until the aged son of the engineer who built the guardians showed him how to disable them. Only then did Ashoka recover the relics and distribute them to stupas across his realm.
A yanta is a mechanism, and bhuta vahana means 'moved by spirits.' The term names a machine that has no will of its own but is animated by an external force. The concept pairs artificial construction with borrowed animation, so the guardian is powerful and tireless but belongs to whoever controls how it was made.
In the legend, the robot-making knowledge originates in a foreign land called Romavisaya. There, robotic assassins hunt down any engineer who tries to leave with the secret. An Indian engineer smuggles the plans out sewn into his own flesh and is killed for it, but his son recovers the knowledge. The monopoly on the technology is guarded by the technology itself, so knowledge can only escape through bodily sacrifice and inheritance.
The guardians cannot be defeated by force; they can only be stopped by knowing their mechanism. Legitimate authority over a powerful machine therefore passes to whoever holds the disarming knowledge, not to whoever holds the throne. Seen this way, Ashoka's rule depends on the engineer's heir, and control of an autonomous system becomes a question of who keeps the know-how across generations.