Productive Land for Agriculture

Land must have plenty of moisture from precipitation or irrigation to produce plants. But irrigation requires precipitation, somewhere,to provide the water. Plenty of moisture we can have only in or from the humid areas.
Irrigation in the Caucasus is possible because of the mountains. Winds passing over the mountains are forced upward, cooled and caused to precipitate their moisture as rain and snow, which in due season provide water for irrigating the land.