How do people get ancient armor before joining any faction?

[Secret]

I see a lot of people talking about collecting the 3 pieces needed prior to joining either camp, yet I've only managed to find one. The guide then describes all the other pieces as being either locked behind main story progression, or requiring misty step (which, AFAIK, I cannot cast until after progressing main story). What am I missing?

[UL]

The ruin raider quest gives you another 2 pieces. Besides that you can find 1 in a dungeon which you already found. The remaining 6 pieces require story progression.