Complex sentence: Documentation from the last years of Ashurbanipal's reign is very scarce but the latest attestations of Ashurbanipal's reign are of his year 38 (631 BC), but according to later sources he reigned for 42 years (627 BC).
Split into simpler sentences: Documentation from the last years of Ashurbanipal's reign is scarce. The last attestations of Ashurbanipal's reign are of his year 38 (631 BC), but according to later sources he reigned for 42 years (627 BC).