This study inquires the political, cultural and economic grievances of indigenous Sindhis and role of the actual or perceived injustices for the rise of Sindhi ethno-nationalism. One-Unit was a scheme introduced by the Pakistani government to amalgamate all the areas of West Pakistan in a single province. Its implementation deprived existing provinces of their autonomy. The defunct provinces were not mere administrative units but were historical homelands of communities possessing distinctive ethno-cultural identities. Hence, it was not only a loss of political autonomy but was also a loss of identity for the people of smaller provinces. Larger proportion of One-Unit population belonged to the former province of Punjab. Punjabis also formed the most advanced ethnic group of West Pakistan. So their dominance in One-Unit's administration, economy and politics was quite obvious. The government was compelled to abandon the One-Unit scheme after a decade and a half because of the resolute opposition by smaller provinces nevertheless it left bitter memories. Indigenous population of Sindh akin to people of other smaller provinces considered the One-Unit period as the bitterest experience of their history. It is abominated as the colonial period during which people had to face many suffering and lead a miserable life. That strengthened ethnonationalists sentiment among indigenous Sindhis. The perceptions of Sindhis' exploitation are how much based on reality demand a comprehensive investigation based on empirical pieces of evidence