Complex sentence: Tarkhan can be both a proper name and a military rank, and it is unclear whether the sources refer to a Khagan, named Tarkhan, or are merely a confused reference to a general.
Split into simpler sentences: Tarkhan can be both a proper name and a military rank. It is unclear whether the sources refer to a Khagan, named Tarkhan, or are merely a confused reference to a general.