Complex sentence: Eventually several of these were successful in carving out parts of Alexander's empire for themselves thereby becoming his official successors or Diadochi, with one of these generals, Seleucus, making this region part of his domain, giving it his name as the Seleucid Empire.
Split into simpler sentences: Eventually several of these were successful in carving out parts of Alexander's empire for themselves thereby becoming his official successors or Diadochi. One of these generals, Seleucus, made this region part of his domain giving it his name as the Seleucid Empire.