react-router

The react-router package is the heart of React Router and provides all the core functionality for both react-router-dom and react-router-native.
If you're using React Router, you should never import anything directly from the react-router package, but you should have everything you need in either react-router-dom or react-router-native. Both of those packages re-export everything from react-router.
If you'd like to extend React Router and you know what you're doing, you should add react-router as a peer dependency, not a regular dependency in your package.