Native american tribes who resented onto their territory would attack any mountain men whom they caught on their tribal lands.

Encroachment.

Explanation:

Between 1868-1890 the encroachment of white settlement and the breaking of agreements made with Native Americans started an endless battle with Indians. White encroachment was highly prejudicial for the Indians, who were forced to live in poor conditions. Native Americans combated white encroachment by fighting white invaders that would enter their land, which happened often.

the completion of the erie canal spurred the first great westward movement of american settlers, gave access to the rich land and resources west of the appalachians and made new york the preeminent commercial city in the united states.