Bhai Kahn Singh Nabha was born at Sabaz Banera in Patiala state in 1861 and served the Nabha court. He was the outstanding Sikh scholar of his generation.
In 1898 he published Ham Hindu Nahin, we are not Hindus, arguing in dialogue form that Sikhi is a distinct religion. It was the decisive intervention in the argument the Singh Sabha and the Arya Samaj were having and it shaped Sikh self-definition for the next century.
His major work is the Gurshabad Ratnakar Mahan Kosh, published in 1930, an encyclopaedia of Sikh literature, history, music, terminology and reference in four volumes, compiled over fourteen years. It remains the standard reference in Punjabi and nothing has replaced it.
He worked with Max Arthur Macauliffe on The Sikh Religion, the six-volume English work of 1909, and Macauliffe acknowledged the debt.
He was a courtier, a lexicographer and a polemicist, and the encyclopaedia outlasted the polemic.
He worked in the Nabha state service and advised its ruler, and the Mahan Kosh was written alongside that work rather than inside a university.
Ham Hindu Nahin, published in 1898, argued that Sikhs are a distinct community, and it was the central text of the Singh Sabha's case in the period.
He also wrote on Sikh music and on the correct reading of gurbani, and compiled a Gurmat dictionary before the encyclopaedia. The Mahan Kosh is the survivor of a working life of reference books.