Blind trails

There is an update on recent research on the Antikythera Mechanism, an Ancient Greek "computer" for calculating calendrical and astronomical events. History is full of these blind trails where a technology was developed, sometimes to a surprising level of sophistication, and then, for unknown reasons, it peters out and is abandoned. The Chinese with their massive ocean-going junks in the Middle Ages is one example but somewhat explicable. More mysteriously (and much earlier), they developed the capability of producing steel which they did for a couple of hundred years before losing the technology completely.

As mysteriously, the ancient Aztecs had the concept of the wheel but used it only for children's toys and never developed it for transportation.

Mysteries of history.