some actual dark ages accomplishments you might recognise:
Beowulf (manuscript dated between 975-1025)
the invention of jury trial (in britain, idk about elsewhere)
Insular artworks and illuminated manuscripts like the Lindisfarne Gospels (c. 715-720)
also includes baller metalwork look at this 7th century sutton hoo shoulder clasp pls
Carolingian artworks and illuminated manuscripts like the Aachen Gospels (c. 800s)
La Chanson de Roland (c. 1040)
national coinage for small kingdoms as well as major empires (in europe) (i know this is earlier in asia)
modern graveyards (in churches, with stone markers)
near-universal literacy (before 1066, as many as 90% of freemen are thought to have been literate in England, including peasants without land) and the promotion of churchmen and administrators from all levels of society
Ecclesiastical History of the English People (c. 731), one of the first post-Classical attempts at evidenced, factual historical writings, covering from 55BC to the 700s, and the stated inspiration for chronicles across Europe all through the medieval period.
the "Celtic cross" and other cool knotwork and animal designs in masonry, generally the result of Viking motifs being applied in areas with better masonry skills
wide distribution of law books
The Book of Kells (c. 800)
the Hagia Sophia (now a mosque, but built as a church by Greek architects in 537)
central heating (really!) (also fun fact: we had central heating in europe before we had chimneys)
grenades (sort of) (they were Greek fire rather than gunpowder explosives but you still throw a small pot at the enemy and it go boom)
Táin Bó Cúailnge and the rest of the Ulster Cycle
English translations of the Bible from the 890s
The Exeter Book (c. 975) which has some absolutely baller riddles in it btw
Ibn Sina's writings on medicine (1020s) - I've tried to stick to a European milieu here (since "Dark Ages" is a European term) and Ibn Sina was Persian. but under the name "Avicenna" and alongside fellow Persian al-Razi/"Rhazes" (c. 864-935) he basically reshaped European medical practices up to the 17th century, so, like. he deserves his flowers.
SOME THINGS THAT ARE NOT FROM THE DARK AGES (a very incomplete list):
common law, parliament, or magna carta
pikes and other polearms (besides spears) (in fact pikes are generally considered to be a sign of the shift from medieval society into early modern)
the poetic edda and prose edda from which we get most of our understanding of "viking mythology" (although they're drawing on earlier sources)
these are all medieval, but became major parts of european society after the 10th-11th century, which is generally the cutoff for "early medieval" or "Dark Ages".
(it's usually the 10th century. England is late to the party, less because of cultural backwardness and more because the Norman Conquest in 1066 provides such a neat dividing line that historians for almost a millennium have been unable to resist making it The Change Of Eras)
