The story
Calque from Chinese 春秋 (Chūnqiū), the attributive sense of 春秋時代 /春秋时代 (Chūn–Qiū Shídài, “Spring and Autumn period”), derived from the name of its seminal history, the Confucian classic Spring and Autumn Annals. The title of the work reflected a common Chinese metonym, using "spring and autumn" to refer to the year as a whole.
Etymology from Wiktionary, CC BY-SA 4.0.