Four Chinese characters - Ving Lac Thong Bao (Vietnamese reading) / Blank. 23mm, 2.39 grams. Issued ca.1730's and later. Toda #-; Barker -; KM -; Remmelts 168.
The characters are taken from the very common 15th century Chinese Ming dynasty Yong Le coins or the Japanese coins copying the Chinese Yong Le trade coins made for circulation in Vietnam. The Vietnamese coins were probably produced in the 1730's and the 1740's. It seems to have been cast in some tin/zinc mixture, not in pure zinc. The coin is not listed in the standard references except for Remmelts.
Nguyễn Phúc Khoát (17141765) was one of the Nguyễn lords who ruled over the southern portion of Vietnam from the 16th18th centuries. Also known as Vo Vuong (roughly Martial Prince), he continued the southern expansion undertaken by his predecessor as lord, Nguyễn Phúc Tru. The Vietnamese-Cambodian border established by the end of his reign remains the border today.