Historians usually focus their attention on the past of countries that still exist, writing hundreds and thousands of books on British history, French history, German history, Russian history, American history, Chinese history, Indian history, Brazilian history or whatever. Whether consciously or not, they are seeking the roots of the present, thereby putting themselves in danger of reading history backwards. As soon as great powers arise, whether the United States in the twentieth century or China in the twenty-first, the call goes out for offerings on American History or Chinese History, and siren voices sing that today's important countries are also those whose past is most deserving of examination, that a more comprehensive spectrum of historical knowledge can be safely ignored.