Excerpts from Books and Wikipedia
" . . . somehow, in the crucible of the Spring and Autumn and Warring States periods, the idea arose that true political authority lies in education and literacy rather than in military prowess. Military men who wanted to rule found they had to garb themselves in Confucian learning if they were to be obeyed and have their sons educated by learned academics if they were to succeed them as rulers." [The Origins of Political Order, Kindle, p. 137]
"By the so-called Spring-and-Autumn period (722-481) there were about 170 such states, each centered in its walled capital. These states formed alliances and leagues and engaged in a diplomatic--military free-for-all, some absorbing others. By the era of Warring States (403-221 BC) only seven major states remained in the competition, most of them on the populous North China plain." [Fairbank: China, p. 49]
The Iron Age began in about 600-500 BC, following the Bronze Age (2200-500 BC). [Fairbank: China, p. 31]
Spring & Autumn (770-476 BC) and Warring States (476-221 BC) periods were the times of Buddha (563-483 BC) and Confucius (551-479 BC).