Complex sentence: They do however have an extraordinary race memory, remembering all of their history starting 33,000 years ago, which is when they first interacted with the wheel-pod trees, an event captured in a story that is their creation myth.
Split into simpler sentences: They do however have an extraordinary race memory, remembering all of their history starting 33,000 years ago. That is when they first interacted with the wheel-pod trees, an event captured in a story that is their creation myth.