Newish Ginger tuned to "Gee, what exactly does that mean?"
General mountain dulcimer or music discussions
When we say "a dulcimer is tuned to G (or D or C)" what we are most commonly referring to is not the key of the song being played (as Dusty so well explains), but the fact that unlike a chromatic instrument like a guitar, we tune the whole (mostly) diatonic dulcimer to a particular keynote. The keynote of the dulcimer is, under most circumstances and with most tunings, the note that the bass string is tuned to.
The Ginger instruments are designed and built to be pitched up higher -- G rather than D or C. Think of it as a soprano rather than an alto or tenor voice. That's not to say you can't put appropriate strings on it and play in C or B. However, the tiny volume of the body means that the instrument won't resonate as good as possible when tuned down that low.

I might start actually playing and singing again soon now that we all survived that first year!!! I've missed you folks!