By Swami Harshananda
Śaṅkara lived in A. D. 788-820.
When dharma (righteousness) aban¬dons its followers because they have ignored it or distorted it, and, adharma (villainy) quickly fills its place, masquerading, perhaps, as a better substitute, God is obliged to intervene! (vide Bhagavadgītā 4.7, 8) He may do so either by directly descending to this earth as an avatāra (incarnation) or by infilling certain chosen persons to accomplish his task of restoring the balance in favor of the former.
During the period preceding the advent of Śaṅkara (also known as Śaṅkarācārya), the Sanātana-dharma (the Ancient and Eternal Religion, now commonly known as Hinduism) based on the Vedas, was facing stiff opposition from several quarters. Buddhism with its śunyavāda (nihil¬ism), Jainism with its śyādvāda or anekāntavāda (which states that a thing can be described in several ways, thus leading to greater confusion), Cārvāka schools (materialism that denied the existence of all non-temporal objects), the Kāpālika and the Vāmācāra cults which propagated unethical and abominable practices in the name of religion—everyone of these was trying to shake the foundation of the religion. It was at such a critical period of the Vedic religion, which badly needed a true and staunch follower to restore it to its former glory, that Śaṅkara was born.
- The Concise Encyclopedia of Hinduism, Swami Harshananda, Ram Krishna Math, Bangalore