Laozi also referred to as Lao-Tzu, Lao-Zi , translated from Chinese "Old Master", was a philosopher of ancient China. He is considered one of the most important philosophers of Chinese civilization and he is held responsible for writing the Dao De Ching or Tao Te Ching, the essential work of Taoism. According to Chinese traditions, Laozi lived in the 6th century BCE. Some historians contend that he actually lived in the 5th-4th century BCE, concurrent with the Hundred Schools of Thought and Warring States period.