As their civilization developed, the Viets' view of the natural world incorporated two forces: equality and balance. In this system, every individual held a god of their own, each balanced out by an anti-god. Due to the belief that these gods could take the form of animals, as well as the belief in individuals' spirit animals to ride into the afterlife, a core tenet of the Viets' belief system was equal treatment of all beings, animals included.
However, as with all belief systems, some adherents diverged. These heretics held more radical, self-serving beliefs that encouraged them to take power over others at any cost. They briefly ruled over the entire Viets tribe, instigating a reign of terror that ended when reformists took matters into their own hands. The leading heretics were killed off, seemingly ending the heretic threat.
Unbeknownst to the Viets at large, some of these heretics fled the tribe to establish their own. Their first order of business was to grow their knowledge of combat magic, likely as part of a greater revenge scheme, only to be met with failure.
Undeterred, the Vieten attempted to craft weapons on a mass scale, but the resulting mass-produced arms were dull and prone to breaking and rusting.