Dear Ravi,
The way the startup had evolved is a story of its own. I echo Simhan, please share what is the purpose, as your story will depend on that.
Suppose you need a press release to highlight your products/services. in that case your story needs to remain focussed on its evolution and the solution that it provides.
A PR initiate to bring the founders to the limelight will need the details of the founders and what inspired them to start the firm.
Weaving a story is easy when you know what is the message you wish to send across.
Looking forward to hear from you