The period known as the Eastern Zhou spanned a considerable number of centuries. It is often sub-divided into the period of the Spring and Autumn Annals, named for the annals of the State of Lu, and the Warring States period, named after another historical text, Discourses of the Warring States. During this time the political divisions of the country were in constant flux as alliances between states were made and broken. The increasing power of the lords of the various states at the expense of the Zhou king probably contributed towards the growth of local bronze industries during this time. Because the head of each state required ritual paraphernalia and arms, the output of bronze objects during this era was substantial.