You can only play with so many civs, but having a large selection of civs is popular. If you have 100 or more civilizations you start getting colors that are too close to each other and there is the chance, even probability, that two civs will come up in the same game that are hard to tell apart. Something similar to primary and secondary colors would work for this if there were some way to let the system detect which colors were "close" to each other and decide which color choices across all the civs produced the best contrast. Alternatively, civs with similar colors could use secondary colors where they border each other. So, we have Bulgaria and Romania next to each other, with Purple and Violet as their colors. This is hard to see, so the system detects the similarity and draws the border between Bulgaria and Romania using their secondary colors, which are Red and Blue. Where Bulgaria borders Greece, which is Green, the border goes back to Violet.