The Extinction Domain was blocked by a vacuum, so all the Cultivation Army from Douglas Country had to do was guard a few entrances and exits. This left an extensive number of cultivators outside, unable only to sigh with longing.
However, they couldn't completely deny people entry. For one, it would look too unseemly, and secondly, the large crowd of cultivators would surely cause widespread chaos if they saw no hope of entry. The costs to suppress such a revolt would outweigh the benefits.
Therefore, the Imperial Court of Douglas Country prepared a batch of access certificates. Anyone who managed to get one would be permitted entry. Regardless of who eventually subdued the Divine Beast Azure Dragon, the court had already made a hefty profit from selling these access certificates; it was a win-win situation.