The grain trade refers to the local and international trade in cereals and other food grains such as wheat, maize, and rice.
The grain trade is probably nearly as old as grain growing, going back the Neolithic Revolution ( around 9,000 BC ). Wherever there is a scarcity of land (e.g. cities) people must bring in food from outside to sustain themselves, either by force or by trade. However, many farmers throughout history (and today) have operated at the subsistence level, meaning they produce for household needs and have little leftover to trade. The goal for such farmers in not to specialize in one crop and grow a surplus of it, but rather to produce everything his family needs and become self-sufficient. Only in places and eras where production is geared towards producing a surplus for trade (commercial agriculture), does a major grain trade become possible.
Early trade was most likely by barter, and because hauling large amounts of grain around was so difficult with ancient technology, the trade was probably quite limited in terms of the volume traded and the area moved. The development of the money economy and the wheel would have facilitated a much more expansive trade.
Care oh, what a beautiful word
For those who had somebody to care
Where they go, what they do, what they say
And if they are happy or blue
Care, wish I could recall how it was
When somebody cared long ago
'Cause the difference is driving me out of my mind
And the difference I'd sooner not know
Life in two dollar rooms and cheap hotels
They mean less and less every day
So if I don't see tomorrow
Well, who's gonna care anyway
Oh care, wish I could recall
How it was and the way our love used to be
But the difference is that I'll always care
And now you don't care about me
Oh care, oh, what a beautiful word
For those who have somebody to just care
Where they go, what they do, what they say