The harmonium is the only instrument most Sikhs have ever experienced Sikh Kirtan through. It came into India via Portuguese missionaries as a more portable alternative to the church organ.
Sadasat Simran Singh Khalsa is a member of Chardikala Jatha, and a Hazuri Ragi at Sri Harimandir Sahib, Amritsar. He lived in India for 15 studying Raga and Sikhism. Here are some things he has to share on the subject of raag.