Age of Warcraft

Research has indicated that before the rise of human civilization, other highly advanced civilizations may have once existed on Earth. It is widely acknowledged that many ancient relics were not created by humanity. In fact, there are numerous monuments that, even with today's advanced technology, we are incapable of building.

Based on such speculations, some scholars have proposed the theory of prehistoric civilizations.

In 1998, within an Egyptian pyramid, archaeologists discovered an artificial heart implanted in the left chest of a boy mummy. Modern medicine has only been producing artificial hearts for the past twenty years, yet this device had been placed in a child's chest over five thousand years ago. This astonishing fact lent further credence to the concept of prehistoric civilization.

Even more shocking, in 2018, scientists unearthed a liquid nitrogen tank at Zhoukoudian near the capital. Inside the tank were five hearts—hearts remarkably similar to those of humans, yet definitely not human.

There are those who speculate these hearts belonged to a species that had not yet fully evolved.

With the advancement of scientific civilization, humanity's longing for immortality has only grown, giving rise to the field of cryonics. As the name suggests, scientists use liquid nitrogen to freeze entire bodies, preserving them in tanks. Theoretically, in a more technologically advanced future, these frozen individuals could one day be revived.

The problem, however, lay in the fact that the liquid nitrogen tank from Zhoukou