Things that were not yet invented

• Horseshoes - were known to the Romans, but lost until ca. 9th century
• Three-field system - ca. 8th century. Prior to that, the more simpler two-field system was used (one field planted, one field fallow)
• Chimneys and fireplaces - basic chimneys started appearing in the 8th century
• Cranes - around 13th century
• Wheelbarrow - ca. 12th century
• Oil paintings - ca. 12th century
• Hourglasses and mechanical clocks - 13th to 14th century
• Blast furnaces and cast iron - ca. 11th or 12th century
• Windmills - ca. 12th century, though the earlier horizontal windmills started spreading in southern Europe in the 11th century
• Compass - probably 12th century
• Paper and the printing press - 13th and 15th century
• Universities - ca. 13th century
• Greek philosophers - their writings and knowledge were lost and re-discovered in the 12th century
• Arabic numerals - 10th century, and not popular until the early 13th century
• Buttons - 13th century
• Silk - 6th century
• Chess - 15th century
• Liquor - 12th century (meaning hard liquor - various beers, ales, meads, etc. were known before)
• Mirrors - 12th century
• Chain mail - 11th century (another technology known to the Romans and lost)
• Scale and plate armour - 12th and 14th century
• Spurs - 11th century
• Crossbow - sporadic mentions from the 10th century onwards. The Romans had crossbow-like weapons
• ...
• (from my head): Concrete, roadbuilding, and large-scale architecture (in Brittain and much of Europe, buildings went backwards from stone and bricks to mud huts)
• Also: Coins (that's important for the game!)
• Aqueducts, of course
• Plumbing
  • also: toilet paper, though it is mentioned in China in 589 AD
• Our Calender - - Dionysius Exiguus creates the Anno Domini system, inspired by the birth of Jesus, in 525. This is the system upon which the Gregorian calendar and Common Era systems are based.

Inventions of the 5th and 6th Century

• The heavy plow turned agriculture upside down and had profound economic impact. For the first time, the heavy, more clayey soils of northern Europe could be farmed efficiently and in fact had higher yields than the previously richer south.
• The stirrup, first invented in Central Asia probably in the 2nd century BC, was introduced to Europe in the 6th century. #AI: The stirrup was a major technological innovation that revolutionized cavalry warfare. Before the stirrup, riders were not able to effectively use lances or bows from horseback. The stirrup allowed riders to brace their feet against the saddle, which gave them much greater stability and control. This made it possible for them to use powerful weapons like the lance and the bow with much greater accuracy and force. The stirrup also made it possible for riders to wear heavier armor, which made them even more formidable in battle. As a result of the stirrup, cavalry became the dominant force on the battlefield in the Middle Ages.

East and West

In the east, the Roman Empire continued. It may be called Byzantin by historians these days, but for a very long time, the people of the Eastern Roman Empire called themselves Romans. Most of the Roman knowledge and technology was not forgotten there, and was transmitted into the Islamic world from where it much later came back to Europe.