All the land of Egypt, i.e. all that part of it; which is a very usual synecdoche.
Related Commentaries of Exodus 5:12
Exodus 5:12
12 So the people were scattered abroad throughout all the land of Egypt to gather stubble instead of straw.
All the land of Egypt, i.e. all that part of it; which is a very usual synecdoche.
12 So the people were scattered abroad throughout all the land of Egypt to gather stubble instead of straw.