Imagine an alternate history in which the first European settlers of Iceland and Greenland were Vikings.
Standard fare, sure, but how about this:
At first these Vikings went about things in typically Viking fashion, complete with Althings, expeditions to Vinland, and grand tales of daring do by warriors set on feasting in Valhalla with the gods.
In their expeditions across the Arctic, through Hudson’s Bay and beyond in search of furs, ivory and trinkets traded up from the South (Aztec gold, perhaps? Lapis lazuli amulets? Strings of gem-like shells?) they ultimately begin exploring the west coast of the continent – eventually coming into contact with the Chinese colonies there.
And so, rather than converting to Christianity these New World Vikings converted to Buddhism.
True to the transcendental traditions of their own goði, these alter-Vikings adopted an esoteric approach to Buddhism, something like Shingon or Tangmi/Mizong – with their practice founded on the idea of Odin as their own boddhisatva, and ultimately developing a tradition of warrior mystics who seek enlightenment through development of their bodies in the fighting arts and various ascetic techniques and mortifications.
In the end, the religious text "The Diamond Edda" would be the foundation of this tradition, and berserk a manifestation of transcendental Zen as the masters of this tradition release attachment to the self and thought and immerse themselves in the moment of battle.
Sun darkened, half-clothed warriors - shaggy in the fashion of the Indian ascetics - would necessarily wander the frozen steppes of the Arctic circle, the crunch of their fur-wrapped feet on the snow nearly drowned by the rhythmic "jingle...jingle...jingle..." as their belled staves strike the ground.
Naturally, their robes would be blood red, their furs white.
And the infidel would weep with terror in the night.