Baij was born in an economically modest family in the Bankura district of the modern state of West Bengal in India. In that sense, he was a Bengali, not an Adivasi, as many people usually think. The surname Baij derived from Boidda (Baidya) and Boijo consequently. His family surname was Poramanik and was abandoned by him in early 1925. His known relatives include his nephew Dibakar Baij and great-nephew Shibaprasad Baij. Ramkinkar Baij was cremated by Dibakar at Santiniketan, and had named him one of his legal heirs. However, many of his artistic creations have been inspired by the lifestyles of rural dalit or Adivasi (Santhal) communities living in and around his place of work Santiniketan.