Chinese scholar Wu Pu suggested the Chinese found commercial colonies in Vietnam. Emphasis mine:
Could be an interesting POD, and certainly more realistic (and profitable!) than Zheng He discovering America or his voyages continuing.
Wu also mentions as possible choices for establishing new international market places, the inlet bay of Thái Bình 太平 in the southern estuary of Red River, and Tân Châu 新洲, called Thị Nại in Vietnamese, the former Champa port located near the ruined capital Vijaya in present Quy Nhơn city. He shows special interest in Tân Châu, which, according to his remark, was an unpopulated buffering zone between Vietnam and Champa, since Vijaya had been conquered by the Vietnamese troops in 1471. He explains Tân Châu as such a desirable place for intermediate trade, and the land in its vicinity so fertile and suitable for farming, fishing and salt making, that it is worth establishing there a colony for overseas Chinese as an international commercial center. Then he suggests resettling the Champa kingdom again in Tân Châu, in order that those Chinese refugees in various places in overseas countries could relocate themselves in Tân Châu, be allocated land and housing for each household, and in the meantime, be organized in the local militia with their leaders as centurions 千百戶. If done successfully, foreign ships would quickly throng Tân Châu, and Chinese merchants from Jiangnan, Zhejiang, Fujian and Guangdong provinces would also go and trade with them. Moreover, if the rebellious Vietnamese rose against the sovereignty of China, the recovered Champa kingdom would provide a strategic footstep and reinforcement for the empire to contain their expansion.
Could be an interesting POD, and certainly more realistic (and profitable!) than Zheng He discovering America or his voyages continuing.