The Mauryan Empire was India's first empire, established in 322 BCE by Chandragupta Maurya. He built a strong army and defeated the Nanda Empire, unifying much of northern India. His grandson Ashoka expanded the empire further after a bloody conquest of Kalinga made him embrace Buddhism and rule through nonviolence. The empire declined after Ashoka's death as later emperors lost popularity and faced rebellions. It was finally overthrown in 180 BCE by the Shunga Dynasty.