Obviously can’t say if it’s the intended way, but I can confirm that a Purge CAN happen in the T1 marked area on the map. That said…
We also had this issue, and the apparent ‘false purge’ until last weekend. I cranked up our Purge settings crazy high, with the calculation timer set to like 5 minutes. On my server, there are only 3 players, in the same offline family, and a single clan… so you can guess which clan gets hit each Purge.
So last weekend, we got the message, 15 minute warning. Checked map, and it was WAY south, in T1 area, by our original homesteads. We ran down to check it out, but as we got closer, realized it wasn’t our base being attacked! 1 of us had setup some switchbacks to climb a pillar. The Purge mobs were attacking THAT. However, there were very few of them - 1 at a time, only about 3 -5 in all, made it to the attack site.
I think a few things are happening-
Purge ‘timer’ is using SERVER TIME, not real time - this would explain 15 or 10 minute warnings, happening too fast. (ie; accelerated day clocks are messing with the Purge timer.)
Purge mobs can/are spawning near, but not at, the target site. They ARE hostile to EVERYTHING. Every thrall, excile, crocodile or world boss, etc. I think many times, they may be getting wiped out before they reach the target.
(edit) Purge mobs are attacking some structure owned by the clan or player, and not actually the target the player THINKS or expects them to attack.
Tonight, we had a near perfect functioning Purge - 1st time. 4 waves of “dogs of the desert,” attacked 1 of our structures (again, not actually a base, but a staircase built up a waterfall.) We got the warning, arrived, and found them attacking the bottom of the stairs. They saw us, and the fight started. Many thralls were captured that day. After the fourth wave, it concluded, we got our Purge survived message, etc. The only flaw, was that they ALL spawned NAKED (yes, server is set to full nude, and we’re using clothing affecting mods - so possibly related to those for sure.)
Other people HAVE reported seeing their Purge attack a world boss on the way - and die. I saw our 1st Purge get mostly wiped out by a camp of Exiles on the beach. So this could definitely be part of the issue.
On that thought, interesting idea; build your base around a boss spawn… instead of a simple box though, build it into a ‘moat’ around your base. Then let the Purge break down the outer wall