W.H. McLeod, a New Zealander who had been a missionary in Punjab, published Guru Nanak and the Sikh Religion in 1968, applying to the janamsakhis the same historical-critical method that had been applied to the Christian gospels.
His conclusions, that most janamsakhi episodes cannot be established as historical and that the tradition developed over time, were standard method and were received in a large part of the Sikh community as an attack.
The controversy ran for thirty years across universities in India, Britain, Canada and the United States, and involved the funding of Sikh studies chairs, the appointment of scholars and, at points, threats.
In 1993 a Guru Nanak Dev University scholar, Piar Singh, was summoned before the Akal Takht over his textual work on the Guru Granth Sahib Ji manuscripts and made to apologise.
The underlying question is real and is not confined to Sikhism: whether a community's sacred history can be examined by the methods used on any other historical material, and who decides.
This site takes the position that saying what is not known is a form of respect, and that a page which marks its gaps can be corrected while a smooth one cannot.
The argument is about applying historical method to the Sikh tradition: dating texts, weighing the janamsakhis as literature, and treating the received account as evidence rather than as fact.
It ran hardest through the 1980s and 1990s between scholars in Punjab and in North American universities, and it was not conducted politely on either side.
Underneath it is a real question about who has standing to write a community's history and by what method, and that question has not been settled anywhere for any tradition.