Complex sentence: After Alexander's death in 323 BCE, his empire was partitioned during the Wars of the Diadochi, following which the competing Ptolemaic and Seleucid Empires occupied various portions of the eastern Mediterranean.
Split into simpler sentences: After Alexander's death in 323 BC, his empire was partitioned. The competing Ptolemaic and Seleucid Empires occupied various portions of the eastern Mediterranean.