The nature of the Mauryan rule required a strong king at the centre on whom, eventually, the strength of (the whole) administration depended. (Dynastic empires depend much on the ability of their kings.)
The officials were selected by the king and they owed loyalty to him. With weak kings, the administrative set-up cracked. The officials were answerable to weak rulers who now ruled for very brief periods.
Thus, the new officials were either forcefully supporting the new ruler or equally forcefully opposing him. Frequent re-alignment of the officials’ loyalties had a disastrous effect.
Local support necessary to run the provincial governments in course of time, fell off as the officials started questioning the centre’s authority, though actually the local officials had a say only in some matters of the administration, the rest was with the centre in Magadha.
Soon after Asoka’s death, Jalauka set up an independent rule in Kashmir, according to Kalhana’s Rajatarangini. Said to be a Shaivite who opposed Buddhist worship, he is described as a great warrior who expelled the mlechchhas.
Taranatha mentions Virasena, another prince, who established himself in Gandhara and Berar or Vidarbha and became an independent king. Greek sources point to the rule of king Sophagasenus in the north (probably, a successor of Virasena called Subhagasena).
The complex spy system that worked efficiently earlier collapsed under the later kings. Corruption and other crimes could no longer be checked effectively.
This resulted in breakdown of other wings of the administration established to ensure proper functioning of the government and hastened the empire’s break-up.
According to the Gargi Samhita, Salisuka, one of Asoka’s successors displayed wanton cruelty during his rule, and this might have hastened the downfall of the empire. At such a point of time, invasions by the Greeks would have dealt a tremendous blow.
Romila Thapar says that the causes of the decline of the Mauryan Empire involved almost the entire spectrum of Mauryan life, adding that the heavy dependence on the king and his inability to rule proved detrimental.
“There were no representative assemblies at that time.” Besides “there were wide economic and cultural differences amongst the subjects which were not suitable” to the ideas of one nation or state.
Asoka had used his Dhamma policy successfully as a solution to socio-political problems and to effectively hold together and run the large empire. This was not a conventional mode of governance and so it was hard for his successors to make use of it effectively.
Moreover, his successors appear to have not attached a great deal of importance to this policy. As for the officials of the Dhamma, it is possible that they gradually took to oppression, especially in the later period of Asoka’s reign.
In his first separate edict (at Dhauli and Jaugada), Asoka asked these officials to be humane and ensure that there was no oppression.
Some scholars have held Asoka’s policies as primarily responsible for the Mauryan downfall. The king’s pro-Buddhist zeal, they argue, with its ban on ritualism and animal sacrifices and the establishment of Dhamma mahamattas could have aggrieved and alienated the brahmans.
Har Prasad Sastri states that the framing of laws by Shudra Mauryan ruler (as the Brahmanas regarded them) could also have resulted in a brahmanical reaction. After all, it was a brahman commander-in-chief, Pushyamitra, who overthrew the last Maurya ruler.
But there is little to suggest that Asoka ill-treated the brahman, and there is no evidence of any united revolt by the brahmans. Asoka’s inscriptions mention the need to respect brahmans as well as sramanas and to have regard for one another’s sect.
It is pointed out that the appointment of the brahman Pushyamitra later as commander-in-chief of the army is itself proof enough that the rulers did not have an anti-brahman policy.
Pushyamitra did not usurp the throne as the leader of the brahmans or of the people at large. The propagation of Buddhism by Asoka could have disturbed the Brahmanical orders but could not have been deep enough to bring about the ruin of the empire.
Asoka’s pacifist policy is recognised as an enfeebling factor: the king’s policy of non-violence weakened the martial spirit of the army, making it incapable of resisting the Greek invasions and suppressing internal revolts. II.C. Roy Chaudhary and others agree with this argument.
Some officials in the provinces had become oppressive and they had to be strictly curbed. As, however, they were not Buddhists, stories in the Divyadhana perhaps narrated the disciplinary measures and the refusal to yield to it as revolts in the provinces.
Furthermore, there is no evidence to show that the military was emasculated in Asoka’s time or that his subjects did not fear the law any more. He did not abolish capital punishment and there is no evidence that he relaxed punishments for crimes.
R.K. Mookheijee’s view is that all empires in India up to the medieval period broke up due to identical causes and the empire of the Mauryans was no exception.
The causes for the downfall of empires were weak successors, repeated revolts due to a need for local-autonomy, oppression by local heads, lack of good communication, treachery by officials and royal intrigues. Scholars of this view blame Asoka only partly for the Mauryan downfall.
Historian D.D. Kosambi identifies inadequate resources and an attempt to increase revenues through new and excessive taxes as one of the fundamental reasons.
Expansion in cultivation, general deforestation and indiscriminate utilisation of all resources may have resulted in famines and floods, reducing state revenue.
The historian also states that there was a greater demand for metals, especially iron, and attempts to find new sources of metals were proving costly. Furthermore, the mining areas had to be protected from the local chiefs by deploying the army.
As a result, the defence expenditure mounted and more taxes were imposed. It is clear from the Arthashastra that taxes were imposed on everything. (There was even a proposal to tax actors, prostitutes, etc.) D.D. Kosambi’s argument was based on the study of the punch-marked coins that showed debasement of currency.
The reduced silver content of what are considered to be later Mauryan coins is perhaps an indication of a depleted resource base.
Romila Thapar, however, believes that economic prosperity did not diminish with the political decline of the Mauryan Empire and the debasement of coinage was not because of reduced material standards, but due to extreme political confusion, in the Ganga valley in particular.
Asoka’s large-scale public works, his tours and the tours of his officials and religious missions within the empire and abroad meant huge expenditures to the treasury.
The Mauryan kings gradually introduced new classes in political life, promoted different religious ideals at different times as and when it suited a particular king, and enforced sanctions in various areas, all of which contributed to disenchantment in general leading to the downfall of the empire.