Patriarchies were originally only those sees founded by Apostles, preferably where one/multiple lived and then died.
Rome had Peter and Paul, Constantinople had Andrew (although... that's a bit iffy), etc.
To get more early Patriarchates, you'd have to get more early accepted legends of Apostolic connexions,
Note that the Patriarchate of Aquileia mentioned above was associated with Mark.
If someone dug up the 'bones' of St. James at (near) Santiago de Compostella several centuries earlier, you could get one there.
The problem with anything in northern Gaul, or worse, Britain, is that no Apostle ever set foot there. This is not an insoluable problem. Glastonbury, say, could be associated with Jesus himself (if the legend is that old, which it probably isn't) as well as Joseph of Arimathea (not technically an Apostle, but..). Add the translation of relics (moving an apostle's bones from their original resting place to the new see), and you can build the case for new Patriarchates. (IIRC, that's what Constantinople did - move Andrew's bones from wherever they'd been.)
Rome had Peter and Paul, Constantinople had Andrew (although... that's a bit iffy), etc.
To get more early Patriarchates, you'd have to get more early accepted legends of Apostolic connexions,
Note that the Patriarchate of Aquileia mentioned above was associated with Mark.
If someone dug up the 'bones' of St. James at (near) Santiago de Compostella several centuries earlier, you could get one there.
The problem with anything in northern Gaul, or worse, Britain, is that no Apostle ever set foot there. This is not an insoluable problem. Glastonbury, say, could be associated with Jesus himself (if the legend is that old, which it probably isn't) as well as Joseph of Arimathea (not technically an Apostle, but..). Add the translation of relics (moving an apostle's bones from their original resting place to the new see), and you can build the case for new Patriarchates. (IIRC, that's what Constantinople did - move Andrew's bones from wherever they'd been.)