An elementary concept of Economic Geography.

The distribution of the continents across the Earth's surface is uneven. In particular, the Pacific Ocean can be thought of as the core of a "Water Hemisphere" facing a "Land Hemisphere" making up the rest of the Earth.

The Land Hemisphere contains over 80% of the world's land and is centered near Nantes in France. This makes Western Europe ideally situated for contact with the rest of the world. Trade, resource extraction, and eventually conquest of the rest of the world are marginally more efficient when based in Western Europe than from other places.

This accident of geography may be the sole reason that Western Europe dominated the world in the 15th through 19th centuries. The onset of technology, especially near-instantaneous communication, reduces (but does not eliminate) this marginal efficiency and allows the rest of the world to emerge from the West's shadow.