3.6. The Persians reuse the jars of imported wine to create stores of water in the desert.
Now I would like to explain something that very few people who sail to Egypt understand. Although clay jars full of wine are imported into Egypt from all parts of Hellasa and Phoenicia throughout each year, there is virtually not even one empty wine jar to be seen there. [2] Where, one might well ask, have all these wine jars gone? The answer is that each demarch must collect every jar from his city and bring them all to Memphis,b where the people of Memphis then fill them with water and transport them to the desert region of Syria just mentioned. Thus a jar makes its way to Egypt, is emptied there, and is then carried to Syria, to be deposited where all the rest of them have been stored.
--- Herodotus, Histories.
By "Syria" he means “This desert is apparently the only land route leading into Egypt. From Phoeniciaa to the boundary of the city of Gaza, the land belongs to the Syrians called Palestinians.” The Persians used this land route to enter and conquer Egypt.