Complex sentence: Unfortunately, the poor preservation conditions meant that all traces of a human body had disappeared but given the strong parallels of inhumations accompanying chariot burials there is no reason to doubt the former presence of a body in the pit.
Split into simpler sentences: Unfortunately, the poor preservation conditions meant that all traces of a human body had completely disappeared. However, given the strong parallels of inhumations accompanying chariot burials there is no reason to doubt the former presence of a body in the pit.