It's out of date, but that's OK when talking historically. And it was no more colonial than saying "Germany" instead of "Deutschland". Personally I prefer the

It's out of date, but that's OK when talking historically. And it was no more colonial than saying "Germany" instead of "Deutschland". Personally I prefer the term "Iran" even for historical usage because it is both older and (usually) more accurate. But "Persian" is not something that foreigners imposed. It was originally the name of a particular Iranian nation that took over the empire thousands and of years ago. Their name then stuck around in some contexts long after that dynasty was gone, which is why the language is called "Farsi" (anglicised to "Persian").