Most Tibetans don’t eat fish, thus most rivers in Tibet are full of fish, except for one, as fishes were blocked from entering the river a hundreds of years ago to prevent the waterwheels from killing the fishes. So why are these waterwheels so important for? The answer is Tibetan incense.
Villagers saw off a bit of cedarwood once in a while and put them in the waterwheel, then the spin grinds out wood slurry. The slurry would be place into molds to produce wood bricks and they would be dried,then the bricks get grounded and get mixed in powders of saffron, musk and as many as twenty other Tibetan native herbs, which can be very expensive on market.
The mixture ends up in another mold and get extruded into strips and dries by the sun. Then comes the essential part-chanting and praying, as Tibetan incense mostly go into temples and surround gods.