The presence of traders and ultimately of miners triggered localized imitation of the parent cultures just as to day urban centers worldwide imitate the major centers. During the Bronze Age these centers were palace oriented polities. In Mycenae, these palaces were made of stone, elsewhere mostly of wood and earth. Regardless, a trader could arrive knowing what to expect and to have solid security for his goods.
Transportation was by sea, and since sea raiding would be uncontrolled, the centers had to be typically built inland unless the center was very large. Subsistence agriculture surrounded all such facilities and provided support. Lack of land mobility limited raiding to reasonable levels and kept a slight control on the regular barbarism normally experienced. However, any reading of the Iliad shows us that every palace maintained a seagoing capacity to meet and fend of challenges from the seas.
Thus the copper economy was both global and focal to every community and organized polity of earth unless completely removed as the Pacific Northwest. The great river basins were not so removed and certainly supported some level of occasional commerce that supported large settled populations.
Over and over the archeology shows extensive artifacts related to the era in question often followed by demise and proceeded by little at all typical of a less organized polity.
Yesterday, I was looking at masses of dinosaur like figurines from Mexico, again dated to the Bronze Age. The numbers were huge suggesting a huge market far in excess of local needs. The images portrayed had also come from a distance and needed explanation. All the problems of a multinational manufactory are sitting there. They likely even had a brand to protect.
Thus we have millions of pounds of copper from Lake Superior and thousands of clay figurines from Mexico. This all represents generational effort carried on with a fair sense of security.
There is a serious need to reconstruct historic population of the basis of likelihood rather than the basis of evidence. Most of the evidence has yet to be found and maps showing a high possibility will inspire study. Recall that pre contact populations in the Americas may have reached 100,000,000. And when we look, we are finding evidence although the need for tribal separation likely kept it much lower; it certainly was very dense in many districts.