Explanation:

 The Nankana massacre (or Saka Nankana) took place in Nankana Sahib at that time of British India, modern-day Pakistan.Sikhs were killed by the Mahant and Pathan mercenaries.The event forms an important part of Sikh history. In political significance, it comes next only to Jallianwala Bagh massacre of April 1919. The saga constitutes the core of the Gurdwara Reform Movement started by the Sikhs in early twentieth century.
The Nankana Sahib Massacre refers to the grim episode during the Gurdwara Reform Movement or Akali Movement in which a peaceful batch of reformist Sikhs were subjected to a murderous assault on 20 February 1921 in the holy shrine at Nankana Sahib, the birthplace of Sri Guru Nanak Dev Ji.