Restoration architect author Anil Laul reasons that poor people used local soil to bake slimmer bricks using locally available cheaper dung cakes as fuel and richer people used higher-end thicker and bigger bricks made of higher strength clay baked in kilns using not so easily locally available more expensive coal, both methods yielded bricks of similar strength but different proportions at different economic levels of strata. Due to the lack of understanding, sometimes contemporary writers confuse the lakhori bricks with other similar but distinct regional variants. For example, some writers use "Lakhori bricks and Nanak Shahi bricks" implying two different things, and others use "Lakhori bricks or Nanak Shahi bricks" inadvertently implying either same or two different things, leading to confusion as if they are same, especially if these words are casually mentioned interchangeably. Lakhori bricks were used by Mughal Empire that spanned across the Indian subcontinent, whereas Nanak Shahi bricks were used mainly across the Sikh Empire, that was spread across Punjab region in north-west Indian subcontinent, when Sikhs were in conflict with Mughal Empire due to the religious persecution of Sikhs by Mughal Muslims. Coins struck by Sikh rulers between 1764 CE to 1777 CE were called "Govind Shahi" coins (bearing inscription in the name of Guru Govind Singh), and coins struck from 1777 onward were called "Nanak Shahi" coins (bearing inscription in the name of Guru Nanak). A similar concept applies to the Nanak Shahi bricks of Sikh Empire, i.e. Lakhori and Nanak Shahi bricks being two similar, but a different type of bricks due to the regional variations as well as political reasons. Closely related similar things may be considered separate, and on the other hand considerably different things might be considered the same, in both cases due to the social-political-religious contextual reasons, for example closely related mutually intelligible Sanskritised-Hindustani language Hindi versus Arabised-Hindustani language Urdu being favored as separate languages by Hindus and Muslims respectively as seen in the context of Hindu-Muslim conflict that resulted in Partition of India, whereas mutually unintelligible speech varieties that differ considerably in structure such as Moroccan Arabic, Yemeni Arabic and Lebanese Arabic are considered the same language due to the pan-Islamism religious movement. Mughal-era lakhorie bricks predate the Nanak Shahi bricks as seen in Bahadurgarh Fort of Patiala that was built by Mughal Nawab Saif Khan in 1658 CE using earlier-era lakhori bricks, and nearly 80 years later it was renovated using later-era Nanak Shahi bricks and renamed in the honor of Guru Teg Bahadur (where Guru Teg Bahadur stayed at this fort for three months and nine days before leaving for Delhi when he was executed by Aurangzeb in 1675 CE) by Maharaja of Patiala Karam Singh in 1837 CE.