According to Mark Doyle, the first cow protection societies on the Indian subcontinent were started by Kukas of Sikhism (also called Namdharis). The Sikh Kukas or Namdharis were agitating for cow protection after the British annexed Punjab. In 1871, states Peter van der Veer, Sikhs killed Muslim butchers of cows in Amritsar and Ludhiana, and viewed cow protection as a "sign of the moral quality of the state". According to Barbara Metcalf and Thomas Metcalf, Sikhs were agitating for the well-being of cows in the 1860s, and their ideas spread to Hindu reform movements. Cattle protection-related violence continued at numerous occasions, often over the Muslim festival of Bakri-Id, in the first half of the 20th century.