Thanks for the link to the paper. 8th century BCE is earlier than long before the earliest meaningful contact between China and Central Asia previously known to me, in the form of the Silk Road. And that's two millennia before the Mongols started having written history!
Also wanted to mention that bronze metallurgy is often considered elitist compared to iron metallurgy because 1)tin ores are less abundant 2) techniques are more intricate. Iron tech is pretty much the first mass tech, if zeroth is fire/fermentation or if those were too easy to be considered tech.
Tin requires a supply chain[1], but bronze requires no special technology to create. Refining iron is much more difficult, which is why we had bronze first.
Pottery long predates ironworking. So does agriculture. I'm not sure how you're defining "mass technology", but ironworking isn't the first one.
[1] It's not just tin. Copper has to be sourced from specific locations too.
Bronze: yeah I should have clarified that for bronze i mean the whole bronze business, including making moulds and such. Iron and steel is like photography compared to painting you need less raw skill to be commercially viable once you can get past acquiring the stuff to get started
Mass technology: I was thinking of programming. You have a class of people distinguished by their skill. Sometimes you even have a representative in the pantheon (Wayland)
