Killing an enemy as a mark of espect, adulthood, and tribal loyalty (in the form of warring between European nation-states) certainly continued on that continent long after society was no longer structured along tribal lines. It didn't end until after WWII. It didn't end on the North American continent after the native tribal structure was mostly eliminated, either. It continues to this very day, although we've decided to take the wars to other countries rather than fight them here. The only real difference is the size of the conflicts and the numbers of people killed.