Earlier quoted context omitted.
Meaning, the grain could have been imported?
Land transport of grain is unlikely. Marine or riverine transport was common in history; you'd have to make some kind of evaluation as to how likely it was in the prehistoric region in question. But assuming it was happening, you still have some sharp restrictions on where it could have come from.
Nobody got from China to Mesopotamia by canoe. Lots of goods were transported by caravan overland, and that certainly included seeds that could be planted to grow useful crops.