Related Clues:
- Coal-producing region
- Essen valley
- Essen's basin
- Mosel River tributary
- European industrial valley
- River past Dortmund
- River that passes through Essen, Germany
- German industrial area
- German coal valley
- Arnsberg is on it
- Essen's area
- Mülheim an der ___, Germany
- Industrial region of Germany
- Where Dortmund is
- Franco-German border region