They’re marshes, and they’re in Iraq. What the? Seriously. And the people that inhabit them staged a minor uprising against Saddam in the 90s. Saddam got pissed, and made a conscious effort to divert water away from the marshes, thus draining them. The people were displaced; the land turned to desert.
But seeds are robust. After the fall of Saddam, some of the diversion banks were breached in order to send water back into the area and restore the marshes.