Ashoka was a warrior and grandson of Emperor Chandragupta Maurya in the 300's BCE. He seized control after his grandfather's death, by killing his siblings.
Early in his reign, he was very brutal and felt quite guilty of how he behaved. He became a Buddhist, and practiced ahimsa (not hurting other living things).
He ruled for 40 years until his death in 232 BCE, trying to treat all people as equals, building roads, wells, and hospitals.
When he died, the following emperors did not think Ashoka was a strong leader, and had weakened the empire. It starting shrinking and splitting apart. Many believe that economic pressures were the undoing of the empire. Ashoka did not tax agriculture or promote trade enough to fund his large military and and bureaucrats.
Ashoka and the following emperors did not use the military and their forces to keep the empire going.