In its earlier history the region was agricultural.
This policy did not allay the discontent of the Macedonian army, and when Alexander in the summer of 324 moved to the cooler region of Media, an actual mutiny of the Macedonians broke out on the way at Opis on the Tigris.
If you travel to a different region, you may find an idiom that you don't understand.
To the west of Lake Van, and close to the headwaters of the Murad Su, the eastern branch of the Euphrates, while the most easterly point is situated in a region about 42° 50' E., southward of the same lake.
But he did not stop short in the region of what is usually termed physics.