[sethrin]

The only problem is that knitting wasn't invented until hundreds of years later.

[Timwi]

But chainmail was a thing, so how did they manufacture it without knitting? Maybe “knitting” is just a way of describing this, while the knitting you're thinking of is specifically knitting involving textiles.

[Ekaros]

Chainmail is made from individual rings. Romans made it from punched out metal rings alternating with rings made of wire and then ends of those rings made out of wire together. Not really too much riveting you can do with textiles. Well maybe plastics, but they did not have plastics.