The poets whose work Guru Arjan gathered into the volume came from several traditions and several centuries, and a number of them came from social positions that the religious establishment of their time placed outside the reach of scripture altogether.
Kabir, a weaver of Banaras, is the most extensively represented, and his compositions run through many of the rag sections. Namdev, from Maharashtra, and Ravidas, of the leather-working community, are both substantially present. Others include Farid, a Sufi of the Punjab, whose couplets stand among the volume's most quoted lines, and figures whose trades, a butcher, a barber, a calico printer, are part of how the tradition remembers them.
Two points need holding together. The first is that their inclusion was not a gesture of tolerance toward outsiders; the compositions are in the volume on the same terms as everything else in it, and a Sikh congregation singing a hymn of Ravidas is not singing an appendix. The second is that inclusion is not annexation. Kabir has his own tradition and Ravidas has communities that revere him in their own right, and the Granth carries a selection of their work rather than the whole of it.
The historical questions about how these compositions reached the compilers, through which collections, in what form and with what alterations, remain open and actively worked on. The atlas records the field as active and does not settle it.