Recent archaeological finds are challenging the long held assumption that civilization first arose in Mesopotamia, Epypt and the Indus river valley and subsequently spread elsewhere. A significant number of contemporary finds dating back to 5000 years ago have been discovered from southern Russia and Iran in an arc to the Indus valley of modern Pakistan. What's more, it appears that these different civilizations had far flung trade networks, with many of the remains at these sites originating from quite distant areas.
"The researchers see evidence of far-flung trade networks for merchandise and ideas: Copper from Oman has been found in Mesopotamia and perhaps in the Indus region; Omani pots have been found in Central Asia. At Gonur in Turkmenistan, the researchers have found seals from Mesopotamia and the Indus region, along with some Iranian goods. And some evidence suggests that carts drawn by bullocks and camels may have been used to facilitate trade as early as the middle of the 3rd millennium BCE. And from Mesopotamia east to the Indus, archaeologists have found massive ceremonial platforms with some common characteristics."
There is good evidence of widespread trading from far earlier, so it should come as no surprise, but this evidence does appear to establish a rather more sophisticated network of exchange arriving long before the written record.