Catholicgauze explains how to figure out a map’s age by checking for known changes, like the reunification of Germany, the breakup of the Soviet Union, or the independence of East Timor. I’ve done this too, actually, but it’s just as much of a challenge for maps and globes produced in the 1950s and 1960s, when colonies were being granted their independence, as it has been for the past 20, turbulent, years. (The 1970s and 80s seem so tranquil in comparison.)