Four Chinese characters - Kang Xi Tong Bao / Yun in Manchu left, Yun in Chinese right, character 索原 (suǒ yuán), punched on the rim at 12 o'clock. Mint in Yunnan, issued in 1682-1689. 24mm, 3.2 grams. Hartill #22.134.

The chopmark is difficult to read - it is probably  索原 suǒ yuán or possibly 素原 sù yuán. suǒ yuán is a private merchant mark, "origin Suǒ", Suǒ being the family name of the merchant who applied this chopmark. These were used to authenticate coins tested for weight and metal quality. This piece was reportedly found in Malaysia, it is possible that the chopmark was applied there.

Countermarks/chopmarks were commonly applied to circulating coins (including Kangxi Tongbao) by private parties, banks, or later issuing authorities - they’re often one or more characters punched onto the surface rather than part of the original casting.

ex-CNG.

The Qing Dynasty, also known as the Manchu Dynasty, was the last ruling dynasty of China, ruling from 1644 to 1912 . It was preceded by the Ming Dynasty and followed by the Republic of China. The dynasty was founded by the Manchu clan Aisin Gioro in what is today northeast China (also known as Manchuria). Starting in 1644 it expanded into China proper and its surrounding territories, establishing the Empire of the Great Qing. Complete pacification of China was accomplished around 1683 under the Kangxi Emperor.This coin is unconditionally guaranteed to be authentic