Complex sentence: In this quasi-legendary era, horse or chariot races, or possibly both, would have been held at the Circus site; the width of the track may have been by the space between the two shrines at the southeastern end.
Split into simpler sentences: In this quasi-legendary era, horse or chariot races, or possibly both, would have been held at the Circus site. The track width may have been determined by the distance between the two shrines at the southeastern end.