Conversely, urbanized peoples have often been in the vanguard of progress, producing far more of the historic advances of the human race than a similar number of people scattered out in the hinterlands -- even when both were of the same race.
Geography has been a factor in this as well, since not all geographic areas are equally suitable for building big cities. The overwhelming majority of cities have been built on navigable waterways, for example -- and not all regions have navigable waterways available.
Isolation can be man-made, as well as created by nature. Centuries ago, when China was the most advanced nation in the world, its leaders decided to isolate the country from other peoples, all of whom they regarded as barbarians. After a few centuries of isolation, China was shocked to find itself overtaken by others, and to some extent at the mercy of those others.
Demography is yet another reason why some groups have very different outcomes than others. Age differences between groups within a nation, or between whole nations, have often been a decade or even two decades. Peoples with decades of difference in experience are almost guaranteed to have different achievements, whether they belong to the same race or to different races.
There are many differences between races that have nothing to do with either genes or discrimination, but have much to do with their educational, economic or other outcomes. However, it is a much harder job to examine these many factors, and their complex interactions, than to seize upon whatever happens to be the prevailing theory of the day that may be both easier to grasp and more self-flattering.