Reports of the western Roman empire's demise were, and sometimes still are, greatly exaggerated. Classical art and culture survived in monasteries, southern Europe and the eastern Roman empire, but new forms arose, most famously the chivalric romance crowded with armoured knightly adventurers, damsels in distress, fierce beasts and enchanters.
(Where for us, of course, "romance" denotes tales of love and feeling, for the Middle Ages it meant simply “from some Latin-derived language like Provençal).
Sir Gawain and The Green Knight is a chivalric romance of the hugely popular Arthurian kind. It is probably our best in English — a frost-sparkling Christmas box of love, magic and adventure but with a strong, though not overpowering, religious gloss. Its only drawback was to have been written in a north-western dialect so unlike what evolved into modern English that it survives today in just one precious manuscript.
[Between 500 AD and 1500 AD new cultures and civilisations arose, and in western Europe the poets of the new code of courtly love held the noble, erotic and spiritual in a permanent state of nail-biting tension.
In The Allegory of Love , the scholar C S Lewis described the new obsession as "love of a highly specialized sort, whose characteristics may be enumerated as Humility, Courtesy, Adultery, and the Religion of Love"]