When he refused to recognise the group's claim that Taiwan is part of China, all hell broke loose.
One of the men from the group, believed to be overseas workers, shouted out in Mandarin "Taiwan, China", and in response Paul yelled "Taiwan, Taiwan".
Paul says that they then "went insane, grabbed poles and started attacking me", while insisting he says that Taiwan is part of China, Taiwan News reports.
Following the attack, he can no longer close his mouth properly. He also suffered a gash to his head, and a fat lip.
In a post uploaded to Facebook, Paul, who has lived in Taiwan for 14 years, warned others to be careful in Cambodia.
He wrote: "In future not going to take my hat off, getting tattoo removed btw, as was a stupid drunken mistake getting it tattooed on my face, any other part of my body would have been fine but not the face, had four laser removals already so flag on chin gone almost already still need a few more for forehead.
"Taiwanese be careful abroad stay safe! Actually I've met many really nice Chinese here in Cambodia but obviously only takes one group that are not so friendly and have trouble."
Last October, Paul made headlines when photos of his head tattoo — along with one of the national flag on his chin which has since been removed — emerged, infuriating his wife.