Sicques, tigers or thieves is a very valuable book having historical accounts on Sikhs from 1606 to 1810. It can be bought at
https://www.amazon.com/Sicques-Tigers-Thieves-Eyewitness-1606-1810/dp/1403962022
It's contents and introduction can be downloaded at https://link.springer.com/content/pdf/bfm%3A978-1-137-11998-8%2F1.pdf
In the introduction it's written:
Of more concern, and a practice that would now be abhorrent, is the
noted practice of forcing Muslim converts into the Sikh faith to take a form of amrit which includes pig blood. Variants of this observation reco