The transition from LaTène C to D1 is generally agreed to have taken place in 120/116 or 120/105 BCE. http://tech.groups.yahoo.com/group/cybalist/message/68398
'As the transition from Middle to Late LaTène researchers unanimously determined approximately one and the same chronological interval - 120/116 or 120/105 BCE.
Dendrochronological research on logs of the Tille Bridge (Switzerland), where all the accompanying finds belong to LaTène D, showed that these logs could have been cut somewhere between 120-116 BCE [Hachmann 1961, p. 258; Polenz 1971, p; Haffner 1979, pp. 405-409].'
It seems to me that that fact rather shows that the transition to LaTène D must have taken place *before* 120-116 BCE, but okay.
Earlier Manching was believed to have been destroyed by the Romans when they conquered the area in 15 BCE. Today most people suggest it was destroyed by someone like Ariovistus some time before 58 BCE.
But could it have been destroyed by the http://en.wikipedia.org/wiki/Cimbri ?
It would seem strange for them to have bypassed this important oppidum in 113 BCE.