Rivers, mountain ranges, oceans, etc. Those are considered "natural boundaries".
the Ural Mountains as well as the Caucus Mountains.
The Alps mountain range forms a natural boundary between France and Italy.
Australia's natural boundry is the ocean.
Natural
Only two mountain ranges separate the continents: Ural & Caucus Mountains.
Lake Victoria acts as a boundary between Tanzania, Uganda, and Kenya. Another natural boundary between these countries is the Kagera River.
The Ural and Caucasus Mountains form part of the natural boundary between Europe and Asia.
The Ural and Caucasus Mountains form part of the natural boundary between Europe and Asia.
diaphragm
Mississippi River
The Ural Mountains serve as a natural boundary between Europe and Asia. This mountain range stretches approximately 1,550 miles from north to south, separating the two continents.