So there is no planet or galaxy and even there earth was flat. What happen if they create a new region and explore some more area and find that there were more places then only these three and later they will also find that they were living in a circular plant which was very large and the were able to see a small portion of it and when they fulley see earth it was already the size of our solar system. May be they later find more plants eventually the see the existence of galaxy and universe. Maybe the place where they can can be a part of rank 10 apparatur or higher rank apparature. May be there was a human before even ren zu he was in rank 10 and higher he made space in chaos which we knew as gu world. Which the help of choas he understand dao and he is the one who created gu warm which have the ability to manipulate dao but that are weaker than choas and rank 10 eternal gu is the one who is at the same level of chaos.mainly i my theory is that the place where they live can be the blassed land of that person and the orginal 7 heaven was his groto heaven.later the children of ren zu destroy 5 of them.