Could the name have something to do with the Pashtun tribe, Shirwani, which became widespread throughout what is Punjab and its members were in important positions throughout North India? Furthermore, just because a name did not exist historically does not mean a culture, people and their history did not exist. India did not exist but Hindustan did - just as Bharat existed before Muslims conquered and renamed it. Sherwani was developed in Hindustan by descendants of Turco-Afghans, Mughals etc. just as they also gave Hindustan their adapted language, food, dress and customs etc. These are the antecedents of Pakistan.
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