The evolution of Hindu Dharma may be divided into three periods: the ancient (6500 BC-1000 AD), the medieval (1000-1800 AD) and the modern (1800 AD to present). The Ancient Period is characterised by the worship of Shiva (Pashupati) during the Harappan times; the composition of the early Rig Vedic hymns; the Epic Period during which the Ramayana and Mahabharata were composed; period of Sage Vishvamitra, in whose reign a majority of the Vedic hymns were composed; the Yajur and Atharva Vedas were composed around 2400 BC; the Bhagwad Gita was compiled between BC 500-200; Nyaya, Sankhya, and Brahma Sutras were recorded, which later gave birth to six popular schools of Hindu philosophy and final versions of Puranas, Tantras and other sectarian literature were developed (200-750 AD). Development of six popular schools of religious thought, establishment of Shankara's Advaita Vedanta and the decline of Buddhism are the main landmarks of this period (750-1000 AD). The Medieval Period saw the rise of devotional movements led by Ramanuja, Ramananda, Tukaram, Guru Nanak, Surdas, Chaitanya, Mirabai, Tulsi Das and many other saints.
The foundation of the Bhakti Movement was laid in South India between the 7th and 12th century AD. Several factors favoured the rise of Bhakti Movement: (a) Hinduism became more ritualistic and dogmatic and was ridden by caste system, which alienated the lower castes; (b) Both Buddhism and Jainism preached extreme austerities and had gradually lost their charm; (c) With the advent of Islam in India, the Sufi saints preached the idea of equality and brotherhood; (d) People were interested in religious thoughts that could satisfy their reason and emotions.
The Bhakti Movement of South India was led by a series of popular saints Nayanars (Shaiviites) and Alvars (Vaishnavites), who disregarded the austerities preached by Jainism and Buddhism but instead preached personal devotion to God as a means of salvation....