AFGHANISTAN, June 26, 2022 (Mundigak): There is very little material on Afghan Sikh history or its origin in the public domain. Roger Ballard (2011) stated that Afghan Sikhs are “likely to be made up of those members of the indigenous population who resisted the process of conversion from Buddhism to Islam which took place in this area between the ninth and fifteenth centuries, and who subsequently aligned themselves with the teachings of Guru Nanak – himself a Khatri and the founder of the Sikh tradition – during the course of the 15th century.”

Guru Nanak came to Afghanistan during the 4th Udasi (1517-21) in the 16th century and it is more likely that the Hindus rather than Buddhists became Nanakpanthis (followers of Guru Nanak). There is no evidence that Buddhism survived in Afghanistan till the 15th or 16th century. The Afghan Hindus are Khatris and Aroras. A small number of them are Brahmins and Bhatias. The present day Afghan Sikhs are descendants of the Afghan Hindus who became Nanakpanthis when Guru Nanak came to Afghanistan in 1521. A large number of Afghan Sikhs shared their surname or sub-caste with Hindus.

An extensive history of Afghan Sikhs and Hindus can be read at source.
https://mundigak.com/en/2020/11/17/afghan-sikhs-tracing-their-origins-and-history/