It has been an amazing year. Lowering a record by 6 seconds is amazing. Though as I mentioned before, having stunning pacers and the colored lights at your feet marking the pace is a big assist. As an illustration of area dominance, the top 500 times ever in this race are by runners from the Great African Rift or a first-generation descendant. The exception is the American Galen Rupp, who still competes and has a half-dozen of those best times. 24th-best is his highest. No one else anywhere.
People will still tell you it's that high-altitude training, though the descendants who live at sea level somehow still manage to be world class. None from the Andes or Himalayas or Rockies or even the Tatras.