Gujri is a section of moderate size in which the devotional poets from outside the Sikh succession take up a conspicuous share of the space, alongside the Gurus and beside var compositions.
Their presence is the single most distinctive editorial fact about the Guru Granth Sahib. When Guru Arjan compiled the volume in 1604 he included the work of poets who were not Sikhs, who belonged to other traditions, and who in several cases came from social positions that the religious establishment of their time placed outside the reach of scripture altogether. A weaver, a cobbler, a butcher, a barber and a calico printer are among them. Their compositions are not appended, not footnoted and not marked as secondary; they sit inside the rag sections under the same headings as the Gurus' own work.
The inclusion was a judgement about content. What was gathered accorded with the teaching, and that was the qualification. Nothing in the volume argues the point or claims credit for it, which is characteristic: the Granth tends to enact its positions rather than assert them.
Later tradition gave the included poets a collective name and a settled standing, and their compositions are sung in congregations exactly as the Gurus' are. The historical questions that remain are about transmission, how these compositions reached the compilers, in what form and through which collections, and manuscript scholarship has been working on them for a century.