Barrier Tag

These tags are special pieces of paper inscribed with the kanji to tie or bind (結, ketsu), which is short for the word "barrier" (結界, kekkai). The tag most likely forms a barrier to protect whatever is located within it. When this tag was used, a shinobi was stationed above it which indicates that the technique might require maintaining.

Trivia

 * There were most likely several other tags and shinobi stationed around the area so as to complete the barrier's formation.