It doesn't matter what sport or league it is, every franchise has its rivalries. In the NHL, the Dallas Stars have one with the San Jose Sharks. It seems odd, but it's true.
These rivalries are important. They keep the fanbase engaged and fire up the players. It adds a little extra edge to those games.
For the Sacramento Kings, their biggest rival is, not surprisingly, California-based. Specifically, it's the Golden State Warriors and that might be part of the reason the Kuminga trade hasn't happened.
Kuminga on the Warriors
The Warriors aren't the dominant franchise they used to be.