Situation: It is not the case that different cultural societies on the different continents were comparable to each other until 3,000 B,C, whereupon western Eurasian societies suddenly developed writing and befan for the first time to pull ahead of other respects.  Instead, already by 3,000 B.C., there were Eurasian and North African societies not only with incipient writing but also with centralized state governments, cities, widespread use of metal tools and weapons, use of domesticated animals for transport and traction and mechanical power, and reliance of agriculture and domestic animals for food.  Throughout most or all parts of other continents, none of those things existed at that time; some but not all of them emerged later in part of the Native Americas and sub-Subaran Africa, but only over the course of the next five millennia; and none of them emerged in Aboriginal Austrailia. That should already warn us that the roots of western Eurasian dominance in the modern world lie in the preliterate past before 3,000 B.C.