Sikh scripture assigns most of its hymns to specific ragas, the melodic frameworks of classical Indian music, a structure built into the Guru Granth Sahib's own organization, and a ragi's training accordingly requires real command of classical raga theory alongside devotional performance skill, since the tradition of gurbani sangeet, sacred music set to scripture, treats correct raga assignment as part of the hymn's proper presentation rather than an optional musical choice.
Traditional Sikh liturgical music historically featured instruments such as the rebab, associated with the tradition's earliest recorded kirtan performance, and later the taus and dilruba, bowed instruments developed within Sikh musical practice, but the harmonium, a portable reed organ introduced to South Asia during the colonial period, became overwhelmingly dominant in gurdwara kirtan through the twentieth century for practical reasons of portability and ease of accompaniment. This shift has become a live point of discussion within some parts of the Sikh community, where organizations and individual ragi jathas dedicated to reviving traditional stringed instrument accompaniment argue the harmonium's dominance has displaced an older and, in their view, more authentic musical practice, while harmonium based kirtan remains by far the most common form heard in gurdwaras worldwide today.