Hyborian kingdoms (and Stygia) vs Yezdigerd

One can read in Conan the Brigand that Stygia refuses to pay tribute to Turan, as opposed to Zamora or Shem; this information is mostly found in part 2 of The Devil in iron, as well as the fact that Yezdigerd raids Ophir, Corinthia, Nemedia and Hyperborea. I had some ideas, quite vague for the moment, about special operations discreetly funded by some of those nations and led, of course, by the PCs, hence my question: is there canon material about countermeasures taken by those nations during (or just before) Conan’s reign? I know that The Hyborian Age presents clashes between Aquilonia and Hyrkanians but I think that it is much later since Aquilonia had at that point already annexed Zingara.

I’ve never seen any Canon material but the Mongoose module The Coming of Hanuman lends itself to this kind of mission. I plan to use it if my PCs start to work against Turan since it involves the elimination of a Turanian general by first joining his army.

The Coming of Hanuman seems really interesting! Thanks, I hope I will be able to find players for it soon.