Why was the horse so significant in the development of the Plains Indian
culture?

Because people ate it.

Explanation:

They were hungry.

I was included in a lot of stories and ceremonies  and helped the Indians travel and fight easier. It was a way faster than walking

from the conditions of the working class in england by friedrich engels,the main idea is :

native americans suffered high rates of poverty and unemployment.

during the late 1960s and early 1970sthe need for political militancy grew among the native americans. throughout the 1960s, they had been the nation's poorest minority group, the most deprived group, according to practically every socioeconomic measure. in 1970, the indian unemployment rate was 10 times the national average, and 40 percent of the native american people were below the poverty line.