Time Barrier

Time Barrier, as its name suggests, was a spiritual shield that renders the ability to freeze time ineffective on those touched by it. This powerful ability seems to be used by priestesses of supreme spiritual power, as Kagome's own modern-day possessions were capable of erecting this powerful barrier on their own instinctively when the Mirror of Stillness activated under Kaguya's will.

However, this was utilized and mentioned only in the Castle Beyond the Looking Glass movie and never in the series itself, so it is unknown whether it would be needed again by either Kagome or Kikyō ever again.

Another thing in Fire on the Mystic Isand movie that Kanade, the priestess of the Hōraijima has built the Cauldron of Resonance with a magical barrier can protects the island from invading Yōkai (especially from Kirinmaru and Zero) that the barrier will fades and holds up every 50 years.

Appearance

 * The bandages and First-Aid Kit glowed with a thin white-green spiritual aura.
 * Cauldron of Resonance

About the Time Barrier

 * "Her possession obviously possess special powers of their own. They must be able to put up a time barrier."
 * "You possess the spiritual powers of a priestess, and can put up a barrier against time. Those powers shall be mine."
 * "The Cauldron of Resonance is awakening. Now the Gates of Time will open."
 * "But every 50 years, when the time barrier becomes weak, demons from the outside world would attack."
 * "The Cauldron of Resonance lost its power. So, now the time barrier is fading away."

Trivia

 * To be overly simplistic, a time barrier only exists around items and people not native to an era. Kagome was not born in the Sengoku jidai, along with all her Modern era supplies and the locket she gave Inuyasha. So this kept them unaffected by the Stillness spell cast by Kaguya.
 * Its unknown if placing anything from the Modern era on Hachiemon and Akitoki Hōjō would have freed them.