Gliders were originally used for spectacles in praise of their patrons. But there was also growing demand for gliders for purposes religious and practical (message delivery). Higher demand for silk lead to better-established trade routes with Arabia, which lead to slightly lower silk prices. When silk prices refused to fall further, Andalusians turned to alternatives such as flax (produced locally), jute (food-quality obtained from Egypt, fiber-quality from India), and hemp (from the Middle East), with efforts to improve trade and grow these plants (plus silk) locally. Trade routes to supply these fibers (as well as cypress wood) stabilized politics from Gibraltar to the Indus for a century until the collapse of the Caliphate of Cordoba around 1000 AD.
During this time, we get the spread of way-towers and updraft-ramps, as well as the first counterweight elevators.
From our discussion on The Alternate History Discussion Forum