After helping kill the monsters along with evacuating the citizens, Shiro received a report from Nan Tian saying that the Asharia in the spirit world has enough space for another city or two worth of citizens but after that it'll be full.
Hearing this report, Shiro couldn't help but furrow her brow since she'll need to make more versions of Asharia if she wanted to keep saving more people.
However, a city like Asharia needed a huge power source. Even with her capabilities, keeping a whole city like that afloat was ridiculously hard and it was only thanks to the anchor that this was possible.
With the increased mana production and divine energy generation, this city could float without her interference. If she wanted to make another city, she'll need to first make a branch anchor before making a city around it.