In the bike boom for club rides and races often nothing more than a toe clip strap holding a spare tubular tire to the saddle rails was used along with a Silca pump on the frame. People who wanted to carry more used small saddle bags and/or handebar bags.
I use the ubiquitous nylon seat bags but over the years I've become less of a weight weenie and use a Carradice lowsaddle longflap so I can bring rain gear, a sweater, etc.