The Roman Map of Britain Arda oneon Hardham, West Sussex

Ardaoneon (R&C 43) next

    Holder suggested a connection with ND's Portum Adurni , traditionally assigned to Portchester (SU6204). This connection is further argued in PNRB's Portus Ardaoni₄₄₁. But as Williams points out, "there is no certainty as to the true location of Portus Adurni".

    Could Arda be the Hampshire river-name Rother? Ekwall considers the name a back-formation from Rotherbridge hundred Redrebrige 1086 (based on an OE hrýðer 'ox', thus 'ox-bridge') and gives its earlier, but not original, name as Shire OE scír 'clear, bright'. Hardham, at the mouth of the Rother, is recorded as Heriedeham 1086 and explained as Heregýþ's hamm. It is possible that both hrýðer and Heriede- are adaptation of a later form of Arda,  *Erið-. See Arduara, where Yarcombe, on the river Yarty,  is recorded Erticoma, Ertacomestoca 1086.
    Hardham (TQ0317) is on the River Rother, and is connected by the Roman road Margary 15 to the next entry Nauimago regentium (R&C 44) Chichester.

    Is -oneon a form of British -ona, a common river-name ending, or a cognate of Latin onus 'a load, burden, freight, tax'?  An oneon might be a taxing-station, or a freight-station and thus a port. From Greek onoV 'ass' is oneion 'ass-stable', if equivalent perhaps a mutatio.

Hardham Camp Roman mansio TQ0317 EHNMR-643041
Hardham Camp Roman enclosed settlement TQ0317 EHNMR-1145352