Also termed a dependent clause, a subordinate clause is comprised of a subject and verb [acting as the predicate], but it cannot stand on its own as a simple sentence because its full meaning is not complete without the independent, or main clause that it modifies. Thus, a subordinate clause is either an adjective clause that modifies a noun of the main clause, or it is an adverb clause that modifies the predicate [verb] of the main clause.
Adjective clauses begin with such as that, which, who, etc.
Adverb clauses begin with subordinating conjunctions such as after, although, because, whenever, if, while, unless, etc.
[For a complete list of the relative pronouns and the subordinating conjunctions, see the link below.]
Therefore, the two sentences can be rewritten in differing ways, depending upon the desired meaning because the words that begin the subordinate clause denote different conditions. Here are a couple of examples using adverb subordinating clauses:
The Indians remained peaceful because (since) the settlers did not steal their land or kill their buffalo.
After the settlers did not steal their land or kill their buffalo, the Indians remained peaceful.