Any doubts about the antiquity of at least parts of the Elegies from the Exeter Book can be settled by a comparison of a phrase in The Wanderer with a phrase in the Old High German poem Muspilli.
The Wanderer, l. 92
Hwær cwom mearg? Hwær cwom mago? Hwær cwom maþþumgyfa?
mearg is here translated as “horse”, in the sense of “war steed”.
Muspilli, ll. 60-61
war is denne diu marha, dar man dar eo mit sinen magon piehe?
diu marha ist farprunnan
“Where then will be the borderland, where one once fought together with kinsmen? The borderland is burnt out.”
marha is here translated as ‘mark, borderland’ (o.e. mearc), but marha or merha also means ‘mare’ (o.e. miere, ‘mare’, from mearh, ‘horse’). It seems the phrase war is marha? war is mag? was proverbial and it has been remembered here, but misunderstood.
Muspilli is a rather messy but pretty wild poem about the Apocalypse, written in the margin of a book belonging to Louis the German around 900. It has been seriously suggested that Louis himself wrote it into his own book. The poem is in old germanic alliterative metre written in a Bavarian dialect and looks like it may be of composite origin.
I have not yet been able to locate any discussion of this parallel in commentaries on The Wanderer and Muspilli, and it is possible it has not been noticed before.
The fact that the OHG passage misunderstands the phrase argues against direct borrowing. I take this as evidence that the phrase Hwær cwom mearg? Hwær cwom mago? (or Hwær is) was proverbial among many Germans and so must either predate the Anglo-Saxon migration or have featured in a story which had very wide circulation, being known both in England and Germany. Either of these possibilities is of enormous significance.