Detailed Instructions: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Q: The Hondo and the Sarstoon River make the northern and southern border .
A:
The undulating courses of two rivers , the Hondo and the Sarstoon River , define much of the course of the country 's northern and southern boundaries .