Post -Mycenaean Greece also experienced some regression, in building, and in the loss of writing. https://en.wikipedia.org/wiki/Greek_Dark_Ages#Culture
https://fr.wikipedia.org/wiki/B%C3%A9ton
https://www.20minutes.fr/sciences/1174563-20130616-20130616-mystere-ciment-romain-enfin-resolu
https://unews.utah.edu/roman-concrete/
https://fr.wikipedia.org/wiki/Machine_%C3%A0_vapeur
https://fr.wikipedia.org/wiki/Feu_gr%C3%A9geois
https://fr.wikipedia.org/wiki/Acier_de_Damas
Here is an example of technological regression in China
1. Crossbows
2.Clocks
3. Pound canal locks - allegedly invented during the Song dynasty, yet they had disappeared by the time when outside observers came to China in the 17th century
4. Ship building. Later Chinese dynasties were unable to build ships even close to the size of the earlier Ming Treasure ships.
5. Items like South Pointing Chariot, and odometer.
https://fr.wikipedia.org/wiki/B%C3%A9ton
https://www.20minutes.fr/sciences/1174563-20130616-20130616-mystere-ciment-romain-enfin-resolu
https://unews.utah.edu/roman-concrete/
https://fr.wikipedia.org/wiki/Machine_%C3%A0_vapeur
https://fr.wikipedia.org/wiki/Feu_gr%C3%A9geois
https://fr.wikipedia.org/wiki/Acier_de_Damas
Here is an example of technological regression in China
1. Crossbows
2.Clocks
3. Pound canal locks - allegedly invented during the Song dynasty, yet they had disappeared by the time when outside observers came to China in the 17th century
4. Ship building. Later Chinese dynasties were unable to build ships even close to the size of the earlier Ming Treasure ships.
5. Items like South Pointing Chariot, and odometer.