Amardeep Singh has self-published the book and will launch it on January 30 at the National University of Singapore.
An Indian-origin Singaporean has documented Sikh heritage in Pakistan in a travelogue which includes historical sites many of which are now ruined due to lack of maintenance since the 1947 partition.
Amardeep Singh has spent more than two years doing research work and visiting Pakistan to put together the 500-page book "Lost Heritage: The Sikh Legacy In Pakistan".
The book has pictures of Sikh temples, including the birth place of Sikhism founder Guru Nanak, mansions and forts built by Sikh ancestors as well as one by legendary army leader Hari Singh Nalwa who built it in the 18th century at Haripur.
Mr Singh, 49, left his 21-year-old executive post at the American Express in 2013 "to do something different" and plunged into full-time history research.
During his visit to Pakistan in 2014, he also saw many of the buildings abandoned and crumbling while others have been turned into libraries and storehouses with some occupied by poor families, he noted.
Mr Singh has also called on the Sikh diaspora to work with the Pakistani government and preserve some elements of the community's heritage in their previous homeland.
"A few hundred years from now, none of these places will exist. They are about to fall apart; they won't last more than 10 to 15 years," said Mr Singh in an interview with The Straits Times today.
The heritage was a part of Sikh Empire in the late 1700s. But today, Sikh population has shrunk to about 20,000 in Pakistan, a country of 182 million Muslims.
"If I don't document it, who is going to do it," said Mr Singh, recalling his father's memorable stories of legacy left behind during the mass migration in which members of his extended family were killed in the ensuing massacres.
Mr Singh has self-published the book and will launch it on January 30 at the National University of Singapore.