Nine Schools of Thought in the context of "School of Naturalists"

The School of Diplomacy (simplified Chinese: 纵横家; traditional Chinese: 縱橫家; pinyin: zōng héng jiā; lit. 'School of the Vertical and the Horizontal') refers to a set of military and diplomatic strategies during the Warring States period of Chinese history (476-220 BCE), aiming for power balance among the strongest Qin State and the other weaker states. According to the Book of Han, the school was one of the Nine Schools of Thought (Chinese: 九流; pinyin: Jiǔ Liú). Originated by Guiguzi, the School of Diplomacy's main adherents were Gongsun Yan (zh), Su Qin, Zhang Yi, Gan Mao (zh), Sima Cuo (zh), Yue Yi, Fan Sui (zh), Cai Ze (zh), Zou Ji (zh), Mao Sui, Li Yiji and Kuai Che (zh) as detailed in the Annals of the Warring States.

By the time of the Warring States period, the major contest was between the powerful State of Qin situated in the west, and the other six mid-power, namely Yan, Zhao, Wei, Qi, Chu, and Han. The seven states engaged in a complex series of pacts and military alliances, commonly referred to as the Horizontal Alliance and Vertical Alliance, based on two geographic patterns. The Horizontal Alliance (连横, liánhéng), adopted by Qin, followed a west–east alignment aimed at curbing the coalitions of the other six states. In contrast, the Vertical Alliance (合纵, hézòng) formed a north–south alignment among the six states to block Qin's further expansion. The spokesperson for the Vertical Alliance is Su Qin, while the spokesperson for the Horizontal Alliance is Zhang Yi.