It is all a terra Incognita.
"Somehow Good"
William de Morgan
Even at this time of day much of the English Border is still a kind of terra Incognita to the tourist and holiday-maker.
"In the Border Country"
W. S. (William Shillinglaw) Crockett
The whole subject of vaso-motor paralysis for instance, and of the pathological changes that follow it, is more or less a terra Incognita.
"On Snake-Poison: its Action and its Antidote"
A. Mueller