"Your Majesty, two Spiritual Sages are at the eastern entrance of the city requesting passage to the inner area protected by the grade-4 arrays." A soldier said this to Minos just after entering the area of the imperial palace where the emperor was at the moment.
A group of soldiers from the Black Plain Army and members of the Gray Clouds Sect had just been intercepted by those two envoys from Calvert. With that, those men outside the area protected by the arrays promptly sent a message by communication arrays to one of the soldiers in the imperial palace.
Currently, the arrays purchased by Minos in the Flowers Kingdom protected the core of Dry City and this entire city, not protecting the belt of cities around this area.
Because of this, the group coming from the Evergreen Empire was at one of the entrances to Dry City and not near the heart of that city, where the command center of the Black Plain Empire was.