The powerful decentralized provincial order which emerged in China after the middle of the eighth century was a direct result of the An Lu-shan rebellion of 755–63. After the founding itself, the rebellion is without doubt the most significant event in the history of the dynasty. It transformed a centralized, rich, stable and far-flung empire into a struggling, insecure and divided one. It has long been treated by historians as a turning-point in T'ang history; in recent decades it has even been treated as a major turning point in Chinese history as a whole. Yet, there is a striking disparity between the event and its consequences. Although such a major internal upheaval was bound to have grave and far-reaching effects, could what was essentially a military event have brought about the profound changes which differentiate the second half of the dynasty from the first so completely?

In reality, the changed situation of China after An Lu-shan's rising resulted not merely from the rebellion alone, but had its roots in developments long under way. As preceding chapters in this volume have shown, T'ang political institutions had undergone significant modifications since the beginning of the dynasty. These changes already anticipated the emergence of forms of government quite different in character from those of early T'ang. But it is imperative to distinguish these long-term changes from the specific origins of the rebellion itself. There was nothing inevitable about this event, even though when it came, it caused a tremendous disruption and acted as a powerful catalyst.