Except for a regional delicacy from northern Japan called ruibe, salmon is not traditionally eaten raw. This is most likely because wild salmon can contain harmful parasites. The Ainu people of northern Japan got around this by allowing the salmon to freeze for several days outside before defrosting and eating it, but eating salmon raw was historically unthinkable for most of Japan.  It wasn't until the late 1980s, when Norwegian salmon farmers were faced with excess production capacity, that they tried to market salmon for sushi in Japan. Predictably, it didn't go well at first, but by offering it as a cheap alternative to more traditional fish for sushi, like tuna or yellowtail, it slowly caught on. With a decade of persistence (and savvy marketing), salmon started to become accepted as an ingredient for sushi by the late '90s. Today, it is one of the most popular fish for sushi, not just in Japan but worldwide. That being said, it's still essential to choose salmon wisely, as it can still make you sick if it has not been processed and handled correctly.