With the help of mysterious races, humanity began the process of expanding its territory and establishing its enduring civilization. They eventually created a giant dynasty. According to legend, this dynasty had a civilization and abilities beyond our imagination at the time, but in a big bang that followed, the civilization was gone forever. No one knows the details of this great explosion, and there is no trace to look for related information, and the mysterious race that helped humans disappear with the explosion. The remaining survivors and their descendants set out to rebuild civilized society, even hoping to build a civilized society completely equivalent to the previous one, but this long process is arduous, because almost no one can remember that era. The lack of resources and lack of knowledge seriously affected the reconstruction of this civilization.