About the Caspian sea area today:
- The south is very lush with the subtropical forests of the Iranian provinces of Gilan, Mazandaran and Golestan (although less "tropical" in Golestan)
- The west tends to be lush with subtropical (?) thicket and also forests around Baku and lots of thicket at least up to Derbent
- The north is pretty much part of the Euroasian Steppe but might not have been until the rise of the Khazar empire or earlier --- Scythian empire in the region which might have caused significant deforestation although still has some rich thicket/grove areas left today
And yet, the eastern coast of the Caspian sea seemed to me from almost any image as a dry "wasteland", with almost no thicket and certainly nothing I would name "a forest".
Why are the south, the west and the north of the Caspian sea lush but its east completely dry?