The decline of Mauryas started immediately after the death of Asoka. The fact that Asoka gave up conquests and preached non-violence reacted unfavorably on the military position of the Empire and rendered it weak.
The sons and grandsons of Ashoka divided the empire amongst them and began to rule in independent capacity without owing allegiance to any common authority. The Andhras broke away from the Maurya Empire and set up an independent kingdom under the Satavahanas. The Kalinga too became independent. The Greek came across from Bactria and began to direct plundering raids. In the hour of his confusion Pushyamitra, the commander-in-chief of the tenth and last Maurya King, Brihadratha, killed his master and occupied the throne himself. The death of Brihadratha brought the Maurya rule to an end.
The causes of the decline and downfall of the empire are not far to seek. The Empire of the Maurya was too vast to be governed efficiently. It was not possible to keep the Governors of the distant provinces under effective control. Provincial misrule was a source of weakness to the Empire. The successors of Asoka were weak rulers. None of them was strong enough to maintain the empire intact.