What was a type of entertainment that was dominated by white actors putting on black face.

Minstrel Show

Explanation:

Minstrel Show refers to a performance on stage that originated in the nineteenth century and which included songs, dances and comic scenes that were executed by white actors in blackface makeup. Thus, the presentations usually lasted three acts  in which they mocked, ridiculed and deprived black people of positive human qualities.

he does not belive what the men tell him about the jungle

the characters in string all have major secrets that they strive to avoid revealing throughout the play.