The Zhou Dynasty was established in 800 BCE in western China and divided into two parts - the Western Zhou (1046–771 BCE) and Eastern Zhou (771–256 BCE). Some key achievements and aspects of Zhou Dynasty culture included establishing some of the first planned cities like Xi'an and Luoyang, developing a hierarchical social structure divided by class, advancing architectural designs like wooden structures and the beginnings of the Great Wall, and promoting Chinese language, music, art, political and religious views. The Zhou also introduced the concept of the Mandate of Heaven to justify the ruler's power and developed self-criticism and renovation through the teachings of Confucius.