Ivory and silver knotwork used as a binding for a catholic manuscript, the Sacramentario di Berengario (Italy, late 9th – early 10th century). This piece can be viewed at the museum of the duomo of Monza, in Lombardia, north of Milano.
As far as I could understand, this binding was probably made at or in the style of the monastery of St Gall (in Switzerland and not St Gallo in Firenze contrary to what was described in the Wikipedia page). It was gifted by Berengar I to the Basilica of Monza.
What’s interesting here is that the knotwork looks very… celtic. But in fact that is not an oddity: the monastery of Saint Gall was founded by a monk, Gall (or Gallus) who lived between ~550 and 640-645, and was of Irish tradition. The hagiographic tradition describes him as one of the companions of Columbanus who left Ireland in a mission to Gaul. Research describes him as a gaul who met Columbanus at Luxeuil in the Vosges. Even if its origin story is debated, he is known to have preached in the Lake Constance region and was known in the territory of current Switzerland. He led a life of an hermit in the forest where he instructed monks in the tradition of Columbanus. They perpetuated his tradition after he died and somewhere between 719 and 750, the monastery of Saint Gall was founded. Among other things it would become renown for its scholars and library, and the artist-monks who worked in the monastery produced illumination very influenced by Irish manuscripts. The presence of the Saint-Gall Irish Gospels among other manuscripts would have helped strengthening this sort of “Irish soft power” in the art painted in those manuscripts created in current Switzerland.

Berengar I of Italy (c. 845 – 924) also known as Berangar of Friuli was the lord of the March of Friuli, then carolingian king in Italy, and appointed Holy Roman Emperor until his assassination in 924.

The Wikipedia page for this manuscript is really short. If you have any sources or infos to complement it, please do!
Sources & links
- Dig into the digitized manuscripts of the Stiftsbibliothek from St. Gallen : https://www.e-codices.unifr.ch/en/list/csg/Shelfmark
- Read about the lineage of disciples from Ireland before Saint Gall (left to right is master to disciple) : Abbán 🪶 Finnian of Clonard 🪶 Columba and Comgall 🪶 Saint Gall