So they were working on bit technology pretty early. I can’t believe how long it took to invent the stirrup.
Maybe, but that’s not a curb bit. There’s no leverage action. It’s going to have a similar action to a wire snaffle. You can see ring bits today on the track; I have an old one, maybe 50 years old, connected to a single-joint snaffle. People who write headlines often don’t know what they’re writing about.
Sez here (wiki-wacky) the earliest evidence for something like a saddle was found in the former Assyria, dating to about 700 BC (near the end of that empire, btw). The toe-loop (early version of the stirrup) was in use as early as 200 BC, in India. My wild guess is, both ideas have been around a long time, but just haven't survived in the archaeological record (at least, so far as is known) because they were made of very perishable materials such as fabrics, maybe even woven reeds.