Some of the most important causes of the fall of the maurya empire are as follows:
The Magadhan empire, which had been reared by successive wars culminating in the conquest of Kalinga, began to disintegrate after the exit of Ashoka in 232 BC.
Several causes seem to have brought about the decline and fall of the Maurya empire.
1. Brahmanical Reaction:
The brahmanical reaction began as a result of Ashoka’s policy. There is no doubt that Ashoka adopted a tolerant policy and asked the people to respect even the brahmanas, but he issued his edicts in Prakrit and not in Sanskrit. He prohibited the killing of birds and animals, and derided superfluous rituals performed by women.
The anti-sacrifice attitude of Buddhism adopted by Ashoka adversely affected the incomes of brahmanas. Further, Ashoka appointed rajukas to govern the countryside and introduce vyavaharasamata and dandasamata. This meant the same civil and criminal law for all varnas. But the Dharmashastra compiled by the brahmanas prescribed varna discrimination. Naturally this policy infuriated the brahmanas.
Some new kingdoms that arose on the ruins of the Maurya empire were ruled by the brahmanas. The Shungas and the Kanvas, who ruled in MP and further east on the remnants of the Maurya empire, were brahmanas. Similarly, the Satavahanas, who founded kingdom in the western Deccan and Andhra, claimed to be brahmanas. These brahmana dynasties performed Vedic sacrifices that were discarded by Ashoka.
2. Financial Crisis:
The enormous expenditure on the army and payment to the bureaucracy created a financial crisis for the Maurya empire. As far as we know, in ancient times the Mauryas maintained the largest army and the largest regiment of officers. Despite the range of taxes imposed on the people, it was difficult to maintain this huge superstructure. It seems that Ashoka made large donations to the Buddhist monks which left the royal treasury empty. Towards the end, in order to meet expenses, they were obliged to melt gold images.
3. Oppressive Rule:
Oppressive rule in the provinces was an important cause of the break-up of the empire. In the reign of Bindusara, the citizens of Taxila bitterly complained against the misrule of wicked bureaucrats (dushtamatyas). Their grievance was redressed by the appointment of Ashoka, but when Ashoka became emperor, a similar complaint was made by the same city.
The Kalinga edicts show that Ashoka was much concerned about oppression in the provinces and, therefore, asked the mahamatras not to tyrannize the townsmen without due cause. For this purpose he introduced rotation of officers in Tosali (in Kalinga), Ujjain and Taxila. He himself spent 256 nights on a pilgrimage which may have helped administrative supervision.
All this however failed to stop oppression in the outlying provinces, and after his retirement Taxila took the earliest opportunity to throw off the imperial yoke.
4. New Knowledge in the Outlying Areas:
We may recall that Magadha owed its expansion to certain basic material advantages. Once the knowledge of the use of these elements of culture spread to central India, the Deccan, and Kalinga as a result of the expansion of the Magadhan empire, the Gangetic basin, which formed the heart of the empire, lost its special advantage. The regular use of iron tools and weapons in the peripheral provinces coincided with the decline and fall of the Maurya empire.
On the basis of the material culture acquired from Magadha, new kingdoms could be founded and developed. This explains the rise of the Shungas and Kanvas in central India, of the Chetis in Kalinga, and of the Satavahanas in the Deccan.
5. Neglect of the North-West Frontier and the Great Wall of China:
Since Ashoka was primarily preoccupied with missionary activities at home and abroad, he was unable to pay attention to safeguarding the passes through the north-western frontier. This had become necessary in view of the movement of tribes in Central Asia in the third century BC. The Scythians were in a state of constant flux. A nomadic people principally reliant on the use of the horse, they posed a serious danger to the settled empires in China and India.
The Chinese ruler Shih Huang Ti (247-10 BC) constructed the Great Wall of China in about 220 BC to shield his empire against the attacks of the Scythians, but Ashoka took no such measures. Naturally, when the Scythians made a push towards India, they forced the Parthians, the Shakas, and the Greeks to move towards this subcontinent. The Greeks had set up a kingdom in north Afghanistan which was known as Bactria, and they were the first to invade India in 206 BC. This was followed by a series of invasions that continued till the beginning of the Christian era.
The Maurya empire was finally destroyed by Pushyamitra Shunga in 185 BC. Although a brahmana, he was a general of the last Maurya ruler called Brihadratha. He is said to have killed Brihadratha in public and forcibly usurped the throne of Pataliputra.
The Shungas ruled in Pataliputra and central India. They performed several Vedic sacrifices to mark the revival of the brahmanical way of life, and are said to have persecuted the Buddhists. They were succeeded by the Kanvas who were also brahmanas.