Why is the land west of the Nile greener than the east?


I’ve been looking at maps of ancient civilization lately, and while looking at modern Egypt on Google Earth, I noticed that there’s significantly more green on the west side than the east, and is also greener on the southeast of the Faiyum, between it and the Nile, than it is on the other side. I also recently played Assassin’s Creed: Origins, and the greenery is the same there. Why is this?

In: Biology

Its probably downhill.

Does your map show relief? You should be able to see contour lines indicating uphill or downhill