Once upon a time there was quite a large Parsi population in Pakistan, especially in Karachi. They contributed significantly to the urban landscape of the city, and many buildings, institutes and hospitals are named after them. I think now there are very few Parsis in Karachi. While browsing through a Marg magazine I read an article on the Parsi contribution to the city of Karachi in Marg Magazine. I also came across link about the Nusserwanjee building which is a part of the Indus Vally School of Art and Architecture.
If anyone has old pictures of the Parsis of Pakistan, please do feel free to share them with me.