In my experience, fantasy and science-fiction fans are introverts who like things better than people. (Who can blame them?) I want these readers to know that medieval technology was deep, challenging, and complex. Medieval nerds were fully employed doing interesting, technical things. They didn’t have to be stereotypical peasants, soldiers, or priests.

Technology is the real “magic.” Pre-scientific technology was complex and powerful. Detailed teaching manuals have survived from the Egyptians, Greeks, Romans, and Middle Ages. This list is not exhaustive, but it should help you explore:
 

•    Edwin Smith Surgical Papyrus (appx. 1600 B.C.), an Egyptian medical textbook.

•    On Head Wounds (appx. 400 B.C.) by Hippocrates of Kos. One of a series of textbooks on surgery and medicine. 

•    De Architectura (20 B.C.) by Vitruvius. Ten books on architecture by a Roman engineer.

•    Naturalis Historia (77 A.D.) by Pliny the Elder. A 37-volume encyclopedia compiled over a Roman officer’s lifetime. 

•    De Re Militari (430 A.D.) by Publius Flavius Vegetius Renatus. A detailed description of the Roman military machine. 

•    De Diversis Artibus (1100 A.D.) by Theophilus Presbyter. Technical manual on the chemistry of painting, glassmaking, and metalwork. 

•    De Re Metallica (1556) by Georgius Agricola. A thick, heavily-illustrated manual on mining and metallurgy “from earliest times.” 

We also have modern technical surveys that provide perspective on the evolution of technology:
 

•    A Short History of Chemistry (1937) by J.R. Partington. From the Egyptians to the early 20th century. 

•    A History of Fireworks (1949) by Alan St H. Brock.

•    Out of the Fiery Furnace (1984) by Robert Raymond. An illustrated history of metallurgy from prehistoric times. 

•    Latitude Hooks and Azimuth Rings (1995) by Dennis Fisher. Navigational tools of the Middle Ages. 

•    Harness the Wind (2003) by Leo Brock. The technical evolution of sailing ships from the Egyptians onward. 

•    The Low-Tech Navigator (2004) by Terry Crowley. Low-tech celestial navigation.

•    Gunpowder (2004) by Jack Kelly. Includes a history of the Chinese huo yao, or “fire drug.”
 

You can find these books at Amazon.com. Some are freely available on the internet.