Complex sentence: Sennacherib was murdered in 681-some claim at the instigation of Esarhaddon, though this seems hardly likely, as he was not in a situation to exploit unrest arising from the death of his father.
Split into simpler sentences: Sennacherib was murdered in 681-some claim at the instigation of Esarhaddon. This seems hardly likely, as he was not in a situation to exploit unrest arising from the death of his father.