Well, no, the mythology has him fighting against all kinds of people, notably including the Saracens.
The more typical question would be "is Arthur based on any historical events at all?"
The more typical question would be "is Arthur based on any historical events at all?"
But the further back you go, the less historical they become. And I don't mean in the sense of historical records being less reliable farther back in time; I mean that the characters in the oldest legends are clearly supernatural figures. There is no reason to postulate supernatural figures as having historical enemies. Why would they?
This makes zero sense.
Most of the Arthur "myth" is deliberately constructed fiction by specific authors, rather than folk myths.