Max Pearson presents a collection of this week’s Witness History episodes from the BBC World Service. To mark 50 years since the discovery of the Terracotta Army, we're exploring modern Chinese history. We hear from the man who helped to modernise the Chinese language by creating a new writing system. It's called Pinyin and it used the Roman alphabet to help simplify Chinese characters into words. Our expert guest is the writer, Mark O'Neill, whose book 'The Man Who Made China a Literate Nation' forms the basis of a great discussion about historical language changes throughout history. Plus, a first hand experience of life in labour camps during Mao Zedong’s cultural revolution and the women forced into sexual slavery by the Japanese Imperial army during the 1930s. This programme contains disturbing content. Contributors: Mark O'Neill - writer Zhou Youguang - linguist Jingyu Li - victim of Mao Zedong's labour camps Peng Zhuying - survivor of sexual slavery Yuan Zhongyi - archaeologist Dr Li Xiuzhen - archaeologist Simon Napier-Bell - manager of Wham (Photo: Terracotta Army. Credit: Getty Images)