Paraglider looks like a rather simple device for me. It does not have a complex engine that needs lots of technology to be built. It also does not need a powered aircraft just to be launched. Looking from the side I have an impression that it can cover serious distances along the ridge under right wind. While it is not convenient to have the airways bound to mountain ridges, it could still have had uses like patrolling borders or similar.
I am surprised, why the master that could build a bow, or possibly sails for the ship could not build a paraglider many years ago. What are the reasons why the paraglider is relatively recent invention? Is there something complex about is I am not aware of?