The Pirra system (the land Pirra, the Pirrans, Pirran Pipe) is characterized by magic. To clarify where this question came from, I was wondering whether the magic of the pipe had an enduring effect, at least for a couple of hours. It is stated that the pipe was played in the morning, at noon and in the evening. This led me to theorize that between those specific times, shadows could still penetrate Pirra.
It is stated in Tales of Deltora that ordinary humans could not enter Pirra because 'powerful magic' barred their way. This could be the magic of the pipe but their are numerous reference in Deltora books that the Pirrans could wield magic as well. Without going into further detail, I have come up with a theory of how the pipe and magic worked.
As mentioned before, Pirrans could use their magic (not the pipe) to protect their land from ordinary humans. This was most likely done by some kind of shutting spell, much like the Torans. However, sorcerers were probably able to penetrate this spell and that is why the pipe was played.
It is obvious that while the pipe is played, all evil is suppressed and temporary powerless. I also believe that the Pirran Pipe somehow reinforced the magic of the Pirrans and Pirra itself. This sounds complicated. So, look at it this way: in my opinion their is some kind of connection between the magic, the land Pirra, the Pirran pipe (specifically its music) and the Pirrans. Obviously the Pirran Pipe plays a pivotal role in this system. However since the origin of the Pipe is unknown, it could be that the Pirran's had created the pipe themselves. Perhaps putting a vast amount of their personal magic in this object. Therefore it is hard to say which factor is specifically paramount with regard to the magic of the Pirra system.
This is all very theoretical but I hope this sparks some sort of discussion.
I am still very fascinated by the Pirran Pipe and its origin. It's strange to me that there is not at least some kind of reference to its creation or origin, even some kind of mysterious one. Wouldn't completely have ruined the mystery of the Pipe in my opinion, because Rodda could have been less specific.
It's an interesting question, especially since the magic of the Pirrans underground appears somewhat inconsistent. If lighting the tunnels uses magic (which it appears it does):
The first tribe did not have their piece of the pipe (Glock did), but their magic still worked. However, it must have been more limited than the second, because they could offer no magical help in facing the fear. The raft dwellers of the second tribe did not have access to their piece of the pipe, and their magic did not work. All the tribes magic also continued to work when Lief and company left with the pipe to the Shadowlands. Futhermore, each tribe could not control the lighting of the other tribes' territory, even though the borders would be purely arbitrary since they used to be one nation and were not native to Deltora.
Because the magic was divided by territory, we have to assume there is some link between their magic and community. The first group of Pirrans could not have lit the tunnels if it was dependent only on the pipe. The dependence on community would also explain why the people on the rafts in The Isle of Illusion could not use their magic after leaving their island. But if magic was related just to the strength of the community, then the piper on the isle of illusion would not have been able to maintain such a large illusion alone. It's also true that the people on the isle of illusion all had to believe in the illusion, otherwise the magic would be undone. The easiset conclusion would be that the pipe is a focal point of the magic in the community.
We also know that the shadowlord took a while to recover from each note Lief played, but that it took less time to recover after each note. Since the magic of the pipe should remain constant, we might assume that the strength of evil is what takes time to recover, not that the music creates a sustained magical effect.
I would agree that it is likely the Pirrans created the pipe themselves, since, unlike precious stones, it is unlikely that the land produced the pipe. Since the pipe lasted so many generations without wear, it is also likely that the Pirrans put a good deal of their magic into it.
The first theory that comes to mind that fits all of these facts:
The Pirrans had a great love of music and a great love of magic. The most powerful magic users in the land came together to make a pipe so flawless that the sound would be much clearer, much more exquisite, and much louder than any other pipe. What they created was beyond what they could have imagined, because the pipe not only emanated sound, but magic itself. When played, all Pirrans focused on the flute, further uniting them in their love of music and further strengthening the magic of the pipe. Enter the shadowlord and the music contest. Once split, the music of the pipe no longer blanketed the land in magic, but focused it on the three pieces of the pipe. People still stood behind each piper and still loved music, which allowed the Pirrans to continue to access the magic from generations before them, but in a way limited by the support of the community and the distance that ordinary sound could travel.