When Dragon City just transmigrated, it was a civilization based purely on machines. The constructions of the city, its operations and defenses were all based on various types of machines.
But as they ran out of energy and the failure rate of the machines just kept increasing, many of the sophisticated machines were rendered useless, and they gradually lost the technological legacy from Earth.
Before the rise of the new generation of machines made with the carving of runes and crystal engines, the transmigrators had to temporarily live in the ancient era where they relied on manual labor and beasts of labor.
However, they soon discovered that when the superhumans who cultivated spirit energy and the monsters who had endless power were grouped together, they could bring out power that did not lose to that of heavy construction machines, and to a certain degree, they had power that those cold metals could not compare to.
