The pioneers opened up the hinterlands and west of the continent of North America and effectively settled the territories that later formed the western and mid western states. In doing this they also treated the preexisting inhabitants very badly committing genocide and wiping out vast numbers of the native wildlife (eg the buffalo). On balance perhaps they are not to be proud of.
Just like us today
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It prompted a westward expansion.
pioneers'
it encouraged pioneers to settle farther west and south
It prompted a westward expansion.
It prompted a westward expansion.
it encouraged pioneers to settle farther west and south
it encouraged pioneers to settle farther west and south
it encouraged pioneers to settle farther west and south
The key to answering this question is locating the prepositions. Prep. #1: of. Prep. #2: of. Next, see if there are any nouns or pronouns that can be used as the object of the preposition. Prep. #1: of us. Prep #2: of the pioneers. If it walks like a duck and quacks like a duck...
pioneers of what