The central religious ideas and practices that began during this period. Thoughts of bhakti (devotion to a single god) developed between the eighth and seventeenth centuries. Shankara, Ramanuja, and Basavanna were prominent thinkers of southern India who shaped the idea of bhakti in the south. Understand how Kabir challenged formal religions. Sufis were Islamic mystics that preached love and devotion to God and rejected the Shariat of Muslim scholars. Guru Nanak established Sikhism to preach worship to one God and love for fellow humans. And his successors turned Sikhism into a huge religion that has millions of followers today.