Actually, most all the areas of history I can think of have benefited from "outside" fields, whether it's anthropologists commenting on 6th c. Europe or chemists analyzing traces of lead in the bodies of the sailors of the Franklin Expedition.

Lots of good examples, but Anglo-Saxon history comes to mind: the number of texts is quite small and there have been a very large number of scholars working in it for a very long time. For an area like this, archaeologists, forensic scientists, chemists, etc. have been the ones really bringing in the new information.