Complex sentence: It is common to hear the term, "Oakland Hills" to refer to that section of the Berkeley Hills that runs along the east side of Oakland; but, as a proper name or recognized toponym, it is technically incorrect.
Split into simpler sentences: It is common to hear the term, "Oakland Hills" to refer to that section of the Berkeley Hills that runs along the east side of Oakland. As a proper name or recognized toponym, it is technically incorrect.