 Philosophy in early China underwent a major transformation after the beginning of empire in the late third century BCE. These were the years of the Han Dynasty, in its two parts, the Western Han (206 BCE–9 CE) and Eastern Han (25–220 CE). Some of the main trends, ideas, and thinkers of the more than 400 years of the Han period are discussed in this article. Some of the particularly prominent features of Han philosophy in comparison with that of earlier periods are: increased focus on metaphysics , the prominence of syncretism, new views on language, the rise of naturalism, and debates about methodology. In addition, many of the ideas we associate with Pre-Qin philosophy were developed most fully in the Han. Retrospective interpretation in later years, including during the Han itself, led to our association of some of these ideas with earlier texts and traditions. Many of the “early”, pre-Han Chinese texts were actually compiled or created during the Han (see Hunter 2018; Klein 2010). Even the “school” categories that we often use to classify texts and thinkers from periods prior to the Han, such as “Confucianism” (rujia 儒家), “Daoism” (daojia 道家), Legalism (fajia 法家), and so on, were actually Han period creations. It is no exaggeration to say that the Chinese philosophical tradition was founded as such during the Han.