Confucian texts are not the word of God or gods; their status lies not in a divine origin. Their importance comes from their ancient sources, their attachment to Confucius himself, and the ways in which Confucian scholars and successive dynasties in China promoted the texts, making them both the gold standard for career advancement in government and for the Chinese culture at large. Like the Book of Poetry, the Book of History circulated in a number of versions among the upper classes during the Warring States era. This was a text that Confucius taught to his students and it was believed that Confucius himself had written it. Books were originally written on long strips of wood, particularly bamboo. Confucians of the Han dynasty were essentially scholars of the classics who saw their job as interpreting these classics and that was, in itself, a monumental task. The Spring and Autumn Annals is a good example of their problems.