Guru Ravidas, Raidas or Bhagat Ravidas was a north Indian Sant mystic of the Bhakti Yoga movement who was active in Punjab region in the 15th century.

Ravidas sang  devotional Bhajan Kirtan and many of his writings made a lasting impact upon the bhakti yoga movement.

He was a shoemaker of the Chamar caste and 40 of his earliest writings are included in the Sikh scriptures or the Adi Granth and other s ahve been passed on independently by his traditional lineage.

Ravidas’s writings are catered around social divisions of caste and genderand  promote crossing of sectarian divides in the name of Spiritual unity. The underlying message in his writings is that one is distinguished not by one’s caste (jaat) but by one’s actions (Karma) and that every person has the right to worship Divinity and read holy scriptures.

http://en.wikipedia.org/wiki/Guru_Ravidas