Mackinder saw history being made on the Northwest frontier of India, but the Empire bled to death on the fields of France in fear of what might happen elsewhere, and by the time it got to India it handed over that frontier, out of exhaustion and a growing reluctance to fight for a possession that did not want to be possessed.

NEWYORKER: Faces, Places, Spaces

The risk and return components of the efficient frontier are computed for a specific time period, usually one year.

FORBES: The Efficient Frontier