The Chengjiang Fossil Site on Maotian Mountain in Chengjiang County, 56 kilometres from Kunming, is one of the world's most significant Cambrian fossil deposits. The UNESCO World Heritage site (designated 2012) protects the Maotianshan Shales, which contain exquisitely preserved soft-tissue fossils from the "Cambrian Explosion" — the rapid diversification of animal body plans around 518 million years ago. More than 200 species have been identified here, representing nearly every major animal group alive today.
The Chengjiang Fossil Museum at the site entrance is genuinely excellent — one of the best natural history museums in China, with modern displays that contextualise the scientific significance without dumbing it down. The fossils on display include originals (not casts) of extraordinary quality, and the exhibition explains what the Cambrian Explosion means and why Chengjiang matters in that story. Allow at least two hours for the museum. Access to the actual fossil beds on the mountain above is restricted, but viewing platforms offer perspectives on the terrain. The museum alone is worth the trip from Kunming for anyone interested in evolution.