Stumped. Using TinEye Reverse Image Search, I turned up this Russian site that says it's from South America in the 1920's. The guy in the center is wearing an insignia with Greek letters kappa-chi(?)-gamma.
Notice that each guy has a different home-brew outfit. Looks like the big-head skull is their emblem, but not everyone has it. My guess is that this a gathering of local leaders of an occult society. The pic was posted on Pinterest by someone named Erica Motter.