I'm on the fence about the whole "exploitation" thing. But it's surely false that "trade is the foundation of any economy".
I think it's more accurate to say "trade is the foundation of a market". According to Smith, river-valley civilizations arose because of markets. Markets arose because of specialization. Specialization arose because the rivers allowed more efficient transportation of goods than land (by a factor of 50?).
But for the paleolithic era, most tribes shared goods communally. No trade needed.
Well, for what it's worth Wikipedia article on the paleolithic suggests there is much evidence of trade during that era (referenced, but I don't have the time to research that ATM). But that's beside the point really. The issue here is how we define what economy is and what trade is. But more to the point, trade in general is not a defining characteristic of capitalism, it's not the differentia specifica of capitalism. But I agree that the statement "trade is the foundation of any economy" is too strong in the sense that it's not only trade that is needed to have an economy (you need production, consumption, etc.).
I think it's more accurate to say "trade is the foundation of a market". According to Smith, river-valley civilizations arose because of markets. Markets arose because of specialization. Specialization arose because the rivers allowed more efficient transportation of goods than land (by a factor of 50?).
But for the paleolithic era, most tribes shared goods communally. No trade needed.