<Tr> <Td_colspan="8"> This box: <Ul> <Li> view </Li> <Li> talk </Li> <Li> edit </Li> </Ul> </Td> </Tr> <Ul> <Li> view </Li> <Li> talk </Li> <Li> edit </Li> </Ul> <P> The Warring States period (Chinese: 戰國 時代; pinyin: Zhànguó shídài) was an era in ancient Chinese history following the Spring and Autumn period and concluding with the Qin wars of conquest that saw the annexation of all other contender states, which ultimately led to the Qin state's victory in 221 BC as the first unified Chinese empire known as the Qin dynasty . Although different scholars point toward different dates ranging from 481 BC to 403 BC as the true beginning of the Warring States, Sima Qian's choice of 475 BC is the most often cited . The Warring States era also overlaps with the second half of the Eastern Zhou dynasty, though the Chinese sovereign, known as the king of Zhou, ruled merely as a figurehead and served as a backdrop against the machinations of the warring states . </P> <P> The "Warring States Period" derives its name from the Record of the Warring States, a work compiled early in the Han dynasty . </P>

When was the period known as the warring states
find me the text answering this question