Complex sentence: The Assyrian reconquest effectively ended Nubian control over Egypt although Tantamani's authority was still recognised in Upper Egypt until his 8th Year in 656 BC when Psamtik I's navy peacefully took control of Thebes and effectively unified all of Egypt.
Split into simpler sentences: The Assyrian reconquest effectively ended Nubian control over Egypt although Tantamani's authority was still recognised in Upper Egypt until his 8th year. In 656 BC, Psamtik I's navy peacefully took control of Thebes and effectively unified all of Egypt.