please visit some libraries and look up the times when the raja empires were signing up in favour of jinnah sb,
then look up the formation of democratic republic, dust off the books that notate the deaths of the early leaders like Jinnah, Khan and Mirza.
Then finally get your interest to fancy the formation of the "islamic republic"
and you will probably find a pretty nice rounded answer to your question. No need to spend large money either, your nadra card is valid at all public libraries in Pakistan.