The decline of the Maurya Dynasty was rather rapid after the death of Ashoka/Asoka. One obvious reason for it was the succession of weak kings. Another immediate cause was the partition of the Empire into two. Had not the partition taken place, the Greek invasions could have been held back giving a chance to the Mauryas to re-establish some degree of their previous power. Mauryan Empire began to decline after the death of Ashoka in 232 BC. The last king was Brihadratha was assassinated by his general Pushyamitra Shunga who was a Brahmin.
The factors which led to the decline of Mauryan Empire are as following:
The religious policy of Ashoka
The religious policy of Ashoka antagonized the Brahmins of his empire. Since Ashoka banned animal sacrifice it stopped the income of Brahmins who received gifts in form of various kinds of sacrifices made to them.
Huge Expenditure on army and bureaucracy
During Mauryan age a huge expenditure was done on maintaining army and bureaucracy. Moreover, Ashoka during his reign made large grants to the Buddhist monks which made the royal treasury empty. The Mauryan kings who succeeded Ashoka faced the financial crunch.
Oppressive rule in provinces
The provincial rulers in Magadhan Empire were often corrupt and oppressive. This led to frequent rebellions against the empire. During the reign of Bindusara, the citizens of Taxila complained against the misrule of wicked bureaucrats. Although Bindusara and Ashoka took measures to control the bureaucrats, this failed to check the oppression in provinces.
Neglect of North-West frontier
Ashoka was so busy in carrying our religious activities that he seldom paid attention to north-west frontier of Mauryan Empire. The Greeks took advantage of this and set up a kingdom in north Afghanistan which was known as Bactria. This was followed by a series of foreign invasion which weakened the empire.
Significance of Mauryan Age
A new era was opened in Indian History after the establishment of Mauryan Empire. It was very first time in history that whole India was politically united. In addition, from this period history writing became clear because of accuracy in chronology and sources. Along with this indigenous and foreign literary sources were available in ample form. This empire left records in a large number to write the history of this period.
Also, some important archaeological findings associated with Mauryan Empire were stone sculptures; a tremendous example of typical Mauryan art. Some scholars suggest that message on Ashoka inscription was entirely different from most other rulers which is a symbol of powerful and industrious Ashoka and also he was humble more than other (later) rulers who adopted grand titles. So it’s not surprising that leaders of the nation regarded him as an inspiring figure.