This change was something more than a mere formality, and in what is known as the Warring States period (481-221 BC) six other rulers – Chu, Qi, Yan, Hann, Wei and Zhao – in different part of China likewise adopted the title of king. The new title indicated that these men did not accept that the kings of Zhou enjoyed a position superior to their own; and it reflected the steady growth of their powers. For Qin, this process of expansion reached its culmination after 250 BC, notably in the reign of Ying Zheng (r.246-210). From the mid 3rd century BC the kingdom of Qin embarked on its sustained conquest of China’s six other state. Inset: The First Emperor, as imagined in the 18th century. Below: the terracotta army.