Zhang Zuo
Not much is known about Zhang Tianxi's early life other than that in 354, when his older brother Zhang Zuo formally broke away from Jin, Zhang Zuo created him the Marquess of Changning. Sometime either during Zhang Zuo's reign or that of his nephew Zhang Xuanjing, who became ruler after the violent and arbitrary Zhang Zuo was overthrown in 355, Zhang Tianxi visited the Jin capital Jiankang, and it was this time that his non-standard, three-character courtesy name Gongchungu was apparently joked about, so he dropped the initial character "Gong" and made it Chungu.