On Earth in the future, the Time Traveler visits the peaceful Eloi and is attacked by the ape-like, troglodyte Morlocks.
On Skaro in the past, the Doctor visits the peaceful Thals and is attacked by the mutated, mechanized Daleks.
On Gwydion in the future, Poul Anderson's Tolteca and Raven visit the peaceful Gwydiona and are attacked by the omnivorous mountain apes.
No doubt we could multiply examples. So far, it seems that Anderson's The Night Face fits into this sf tradition. Travelers through space and time meet monsters. However, something is different on Gwydion.