Conventional wisdom now intones that the 21st century will be the Asian century, with power shifting inexorably away from the West toward that vast and, for many Westerners, rather vague entity called Asia. If this is the case, and there are grounds for believing it is, we need to clarify what exactly (or even approximately) we mean by “Asia.”

Geographical terms do not in themselves change the lines on maps, but they do shape conceptions and, consequently, behavior. “Asia” is certainly a term whose meaning has changed with historical circumstances and their contexts. In the heyday of Western imperialism, “Asia” typically referred to everything from Suez to Shanghai, with a particular emphasis on those parts of Asia readily accessible to Western navies and merchant ships. But by the third quarter of the 20th century, a series of events—the War in the Pacific, the rise of a communist regime in China, the Korean and Vietnam Wars, the economic ascent of Japan and the Asian Tigers (South Korea, Taiwan, Hong Kong and Singapore)—both narrowed what we took to be “Asia” and underlined its growing importance. For most purposes “Asia” came to mean the north-south coastal region extending from Korea to Indonesia. The fact that the West’s key strategic interaction with the continent was via American naval power reinforced this vertical, maritime conception of Asia, as did late 20th century efforts at regional organization. Often expressed in the concept of the “Asia Pacific”, this particular geostrategic artifice created some odd legacies: Asia’s preeminent economic and political body, APEC, includes Chile but not India, Mexico but not Mongolia.

The vertical idea of Asia has now outlived its usefulness and serves to obscure reality rather than illuminate or shape it. We are not alone in this belief. Robert D. Kaplan sees the return of an old idea of Asia as a “continent reconfigured into an organic whole” that emphasizes its east-west connections. India’s leading strategic commentator, C. Raja Mohan, speaks of the revival of a Curzonian perspective in Indian foreign policy that also views Asia in whole-of-continent terms. As these ideas gain currency, however, there is risk of encouraging the adoption of one half-truth at the expense of another. Perhaps the most prominent variation thus far on the theme of Asia’s strategic reorientation is one focused on the Indian Ocean. Kaplan anticipates a competition there between the naval fleets of Asia’s two emerging powers, China and India. James Holmes and Toshi Yoshihara argue that China’s growing naval reach prefigures its eventual adoption of Mahanian precepts emphasizing the importance of maritime power. The popular “string of pearls” thesis anticipates China building a ring of bases in the Indian Ocean.¹

But this focus on naval power...