The spread of BUDDHISM from its origins in northern India (roughly 5th century BCE onward) to Central Asia, China, Korea, Japan, and Southeast Asia is a canonical example of:
AWidely discussed in older popular accounts but rarely referenced in modern comparative historical scholarship, and generally regarded today as a minor rather than transformative episode in the broader historical trajectory.
BA minor regional development that had no lasting influence on broader historical patterns and left no durable institutional or cultural legacy in the surrounding areas.
CCultural diffusion of a religion via trade routes, monastic networks, and (in some cases) political patronage — reshaping the religious and cultural geography of much of Asia.
DRepresents a category confusion in most standard accounts, mixing distinct developments that occurred in different periods, regions, and cultural contexts under a single misleading label.
Explanation
The spread of Buddhism from northern India to Central Asia (via the Silk Road), China, Korea, Japan, and Southeast Asia is a canonical example of cultural diffusion of a religion via trade routes, monastic networks, and political patronage (Ashoka in India, various Chinese emperors, various Japanese and Korean rulers). It reshaped the religious and cultural geography of much of Asia over the following two millennia.