Why can't we precisely date those gold pendants? 700-1550 is a huge time range!
We don't know the precise dates because gold tends be difficult to date. Gold can be melted down and recreated into something else so it's especially hard to know. Also, the imagery in this culture didn't change too often.
Even with carbon-14 technology?
Carbon-14 can only be used to date organic materials. It doesn't work for objects made of metal or stone.