Julian marched from Augustodunum (Autun
) to Tricassini or Tricasses (Troyes
), and on his way he went through Autissiodurum, or Autosidorum, as it stands in the common texts of Ammianus (16.2).
This route agrees with the Anton. Itin. and the Table, which place Autissiodorum on the road between Augustodunum and Tricasses.
The place is therefore on the site of Auxerre,
on the Yonne,
in the department of Yonne.
Autissiodurum belonged to the Senones.
A sepulchral inscription dug up at Auxerre contains “civitatis Senonum, Tricassinorum, Meldorum, Pariorum, et civitatis Aeduorum,” but it is difficult to see what conclusion can be derived from this.
The name “civitas Autesiodurum” is not found earlier than in the Notitia of the Gallic provinces.
A patera found near Auxerre bears the inscription Deo
APPOLLINI R. P. II. M. AUTESSIODURUM. (Walckenaer, Géog.,
&c., vol. i. p. 408.)