Accompanied by Sioux prayers and the keening of Scottish bagpipes, a plain cotton shirt was returned to South Dakota this past summer.
People didn't know about the shirt.
It isn't known if people knew about it.
( z0 know :ARG0 ( z1 person ) :ARG1 ( z2 shirt ) :polarity - )
(z0 / know-01
    :ARG0 (z1 / person)
    :ARG1 (z2 / shirt)
    :polarity -)
People did n't know about the shirt .
z0 :polarity 0
z0 :ARG0 z1
z0 :ARG1 z2