First, important cause of the downfall of the Mughal Empire was its unlimited territorial expansion. From Babur down to Aurangzeb the Mughal Empire had continuously extended its territorial limits.
The limits of the empire covered a vast area from Arsam in the east to Kabul in the west, and Kashmir in the north to Mysore in the south.
In those days of primitive communication it was impossible to maintain strict control over such a vast area from its capital Delhi.
Second, in the prevalent system of Mughal government the emperor or the Badsah was the sole powerful man. In such a system the ability and personality of the emperor was the single most important factor.
The great Mughal Empire built upon the genius of the great Mughals (Babur to Aurangzeb) showed signs or decay after the death of Aurangzeb.
The successors of Aurangzeb were all weak persons, unfit to be the rulers of so vast an empire. Taking advantage of the weakness of the central government the provincial governors declared independence in their respective areas of control.
Third, the weakness of the military system was another factor responsible for the fall of the Mughal Empire. Apart from the lack of discipline the Mughal soldiers had to fight with ineffective weapons.
Moreover, the luxurious habits of the Mughal generals also led to the loss of efficiency in the army.
Again, the Mughals were not aware of the threat from the European countries and, therefore, never paid any attention to build up a strong navy.
Fourth, towards the end of the Mughal rule the imposition of high revenue demand overburdened the peasantry.
Though various other factors were responsible for the outbreak of rebellions, the discontent of the peasants due to tax- burden constituted the main cause.
At the initial stage the rebellions took the form of sporadic outbursts but in course of time the rebels made a concerted move through religious communities such as the Sikhs and the Marathas.
In any case, the rebellions adversely affected the stability of the Mughal Empire that led to its fall.