  Supernova remnants (SNRs) are important objects in terms of their connections
with supernova (SN) explosion mechanism(s), progenitor stars, and cosmic-ray
acceleration. Non-thermal emission from SNRs is an effective probe of the
structure of their surrounding circumstellar media (CSM), which can in turn
shed lights on mechanism and history of the elusive mass-loss of massive stars.
In this work, we calculate the time evolution of broadband non-thermal emission
from SNRs originating from Type II SNe embedded in a CSM environment linked to
the mass loss history of the progenitor. Our results predict that Type II SNRs
experience a prolonged period of weak radio and $\gamma$-ray emission if they
run into a spatially extended bubble of low density and high temperature
created by the stellar wind during main sequence. For a typical red supergiant
progenitor evolved within an average interstellar medium (ISM), this "dark age"
corresponds to a range of SNR ages spanning from ~1000 to 5000 yrs old. This
result suggests that a majority of Type II SNRs are too faint to be detected,
which may help explain why the number of known Galactic SNRs is significantly
less than what we expect from the SN rate in our Galaxy.
