What factors might help explain the fact that a powerful, centralized state like the Tang dynasty in China never arose in India after the collapse of the Guptas?
My textbook is Bentley and Ziegler's Traditions & Encounters.
Differences in prior dynastic governance and circumstance are among the most important factors in accounting for the fact that a strong centralized state dynasty never arose in India as it did in China.
In India, the Gupta Empire ushered in the so-called “Golden Age” of India, during which feudal lords and noblemen prospered under the relative leniency of the Guptas. Many lands adopted to pay taxes to the empire voluntarily since the Guptas provided strong military protection to the otherwise vulnerable communities that lay along the border of the Indian sub-continent. In addition to self-protection, the Guptas offered strong economic incentives for alligence. They consistently patronized the arts, scholarship, the sciences and the religious priesthood, thus supporting a growing aristocracy and intellectual elite. Finally, the Guptas were non-punitive and relatively merciful in issues of law and justice. One notable example: not a single line in the Gupta Empire employed the use of capital punishment for any crime. The Guptas left the population of the Indian subcontinent in a state of peace and prosperity. As a result, when the Gupta Empire did collapse, things were stable and there was no need for radial economic, cultural, or social reorganization.
The Tang dynasty emerged under radically different circumstances. The prior Sui Dynasty left the Chinese population in a state of crisis; famine, terror, and inter-clan violence were extremely high. The Sui Dynasty was strict and harsh. It made excessive demands of money and labor upon its lands, and left many feudal lordships in a state of chaos in its wake. Thus, following the collapse of the Sui Dynasty, the population desired ugent, substantial reorganization and a shift in the dynastic culture. This desire created the groundwork for acceptance of a state dynasty that promised prosperity, safety, and mercy to its empire.