The reigns of Dharmapala and Devapala formed the period of ascendancy of the Pala dynasty, after it was established by Gopala. Starting from that instance the Palas felt powerful enough to venture out in the political arena of north India. Both Dharmapala and Devapala were engaged in a long drawn struggle for possession of Maddhyadesa of the north Indian empire, with two other powers- Gurjaras and Pratiharas of western India and Rashtrakutas of Deccan, and they had achieved success for a limited period. Dharmapala succeeded in placing his vassal to the throne of Kanauj. Devapala also had held his own against the Pratiharas. Till the time of Devapala, Bengal was reckoned as an important power in the history of ancient India. But the period that followed the death of Devapala was marked by decline and disintegration of the Pala Empire, under the impact of foreign invasions.

With the death of Devapala the period of ascendancy ended and a period of stagnation followed, which gradually led to decline and disintegration, until it was again restored by Mahipala I. After the death of Devapala, the throne was ascended by Vigrahapala I, who ruled for a short period, with unimpressive records and was succeeded by his son Narayanapala about 854 A.D. However Narayanapala did not possess that majestic temper like his predecessors. He was a man of religious and pacific disposition and hence during his long career of 854 to 908 A.D., he did not have any military victory to his credit. Historians ascribe him as one of the weak kings of Pala lineage. In 860 A.D. when the Rashtrakutas had invaded his Empire and inflicted violent defeat on him, his power and prestige was reduced considerably, which was indeed unmanageable for him to restore. In due course several overrides also followed in quick succession. The Pratiharas, hereditary and persistent enemy of the Palas in Bengal, struck several blows on the Pala Empire, under Narayanapala, till the Empire was broken to pieces. Bhoja I snatched the imperial hold of North India from the folds of Pala king Narayana Pala. Bhoja I thereby extended his own sway upto the farthest limits of Bihar, on the ruins of the Pala Empire. Mahendrapala, son of Bhoja Pratihara followed a relentless policy of aggression against the Palas and made penetrating conquests in the core of Pala kingdom, by seizing Magadha and even the territory of north Bengal from Narayanapala. The "Paharpur Pillar Inscription" states that Mahendrapala Pratihara had conquered a part of the Rajshahi district and the other inscription states that his sway had extended upto the region of Dinajpur. In these circumstances the king of Kamrupa withheld his allegiance for the Palas and the Sailodbhaba dynasty of Orissa, which used to be a vassal state of the Palas, unfurled the flag of independence, taking advantage of the weakness of the suzerain authority. Towards the closing of his reign perhaps Narayanapala was able to recover North Bengal and South Bihar from the powerful contenders Pratiharas, and left it as a legacy to his successor Rajyapala in 908 A.D.

Rajyapala however reigned for a very short period of time. He was succeeded by his son Gopala II and the latter was succeeded by Vigrahapala. The long period of eighty years, when these three kings were in throne, was marked by augmentation of the process of disintegration and decline of the Pala Empire. Moreover a series of foreign invasions led by the Chandellas, Kambojas and Kalachuriyas during these three Pala kings had shattered their decaying fortune into pieces. The Kalachuriyas made devastating inroads in Bengal, right upto eastern Bengal. During the reign of Vigrahapala II, a hilly tribe called Kambojas had captured western and Northern Bengal. Eastern and southern Bengal also overthrew their allegiance towards the Palas and became independent under the Chandra Dynasty.

Towards the end of 10th century the Pala power sank into deep obscurity under the relentless pressure of foreign assault and internal disruption. This had accentuated the downfall of the Pala Empire. The paternal territory of Rajyapala and his two successors consisting of Bengal and Magadha, were divided into three well-defined independent kingdoms. These included- Chandra kingdom of eastern and Southern Bengal, Kamboja kingdom of Northern and Western Bengal, the Pala kingdom (proper), under Rajyapala and his two successors, comprising Anga and Magadha. The period of stagnation that followed the succession problem continued for more than a hundred years, covering the reigns of generations of kings. During this period the Pala kings were lacking in energy and vigour; there was hardly any attempt for expansion, and they were not powerful enough to check invasions from outside (of the Chandellas and the Kalachuriyas towards the end of 10th century A.D.) or uprisings from inside. Hence the downfall of the Pala Empire was inevitable under these weak successors after Devapala.