Maxwell Lord visits Egypt to buy oil wells from Emir. In this segment, we see the wall raise suddenly in Egypt:
Why did the wall raise suddenly in Egypt?
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The Emir wished for all his ancestral lands to be returned to him, and for all the people he regarded as heathens to be kept out forever. He didn't know this wish was actually going to come true when he made it, but it did, and that wall was presumably the means of keeping the "heathens" out.
MAX: Tell me what you wish for, Your Highness, and I will show you how it works.
EMIR: I wish for things one cannot attain.
MAX: Like what?
EMIR: All of my land to be returned. My ancestral realm. The Bialyian Dynasty. And for all the heathens who dare trod upon it to be kept out forever, so that its glory may be renewed.
MAX: You wish for that?
EMIR: I wish for that deeply.
MAX: Your wish is granted.
Wonder Woman 1984