The language of the Ae Laa

In the vast and lonely seas between Tallspire and Aarang, there is an island. The island is like many in Klissidar: neither particularly large nor particularly small, with thick jungles and a knob of mountains at its interior. Its people, though, are special. Unique among the vast swath of civilizations across the archipelago, the Ae Laa speak a language that no outsider has ever been able to translate.

There was no consistency, no consistency at all. Sometimes I would hear an entire conversation consist of the same two phonemes, repeated over and over. Other times whole days would go by before I heard the same sound twice. I listened for tonal inflection, I watched body language, facial expression: nothing. It really seemed like these people were making random noises – except that they all understood each other perfectly.
– Inu Anabek, Klis linguist

The chimeric cipher of the Ae Laa language stands at odds with their lifestyle, which is shockingly mundane. The Ae Laa all seem to dwell in small agrarian villages on the shoulders of the mountain. They farm rice and fruit, raise chickens, build wooden houses, weave and dye cloth; metallurgy, artifice, and magic seem to have no presence in their lives, nor does warfare. If it weren't for their bafflingly opaque language, no one would have taken notice of the Ae Laa at all.
Indeed, the name for the island and the people who dwell there is nothing more than a stab in the dark. Inu Anabek, the first linguist from the Collective to visit the island, catalogued 87 phonemes spoken there, of which the pair "Ae Laa" (usually but not always spoken as a pair) constituted a clear majority. However, the frequency with which these sounds are deployed varies tremendously, for no apparent reason. What appear to be situationally-similar conversations (someone buying fruit from a vendor on two consecutive days, for instance) don't use any of the same words. Large groups of people are able to communicate around complicated tasks like a village barn-raising while only using, with no tonal inflection, the two syllables "Ae Laa." There does not appear to be any written form of the language.
The Collective, with its hundreds of spoken languages, has no shortage of linguists, and once the word got out many of them descended upon Ae Laa. When intellectual analysis failed, they turned to magic. The usual linguistic divinations, unreliable at the best of times, proved worthless, but, surprisingly, even advanced telepaths made no headway: the Ae Laa seem completely immune to psychic communication and infiltration. No progress could be made in teaching the Ae Laa to speak Spire or any other language of the archipelago, either; most were uninterested, while others would solely pick up the word "Yes," which they would use in response to any query.
Many of the linguists who investigated the Ae Laa developed an obsession with cracking the puzzle of their language; some even began to harbor animosity towards the people, wondering if some elaborate hoax was being perpetuated out of malice or cruelty. Indeed, the impenetrability of the language is particularly puzzling in light of how many gestures the Ae Laa do share with other peoples: they wave hello and goodbye, shake hands, kiss. Often, small groups of Ae Laa would point at the linguists poring over their useless notes. "Yes, yes," they would say, and point, and laugh.

They're hiding something. They're hiding something. They're hiding something. THEY'RE HIDING SOMETHING.
– final diary entry of Rowan Tehregawa, Kahalit linguist

There has been only one attempt on the lands of the Ae Laa by force. Fearing the implications of an undecipherable populace with opaque motivations on their vulnerable southeastern border, Tallspire sent a battalion to the island to establish fortifications and extract military intelligence, taking prisoners if necessary. A token squad stayed behind to secure the beachhead while the bulk of the force proceeded inland. After days had passed with no communication, a scout followed the battalion's trail until he came upon a village, where all traces of the company vanished. The farms, houses, and orchards stood peacefully. On the village outskirts, the scout found the battalion's captain, weapons and armor discarded, working peacefully in a rice field alongside several Ae Laa and seemingly speaking fluently to them in their own language. The other soldiers were never found.

The captain smiled at me, but it was the blank kind of smile you give when someone you don't know is acting strangely. He didn't recognize me.
'Captain,' I said, 'what happened?' and he spoke to me in that damnable language, and kept smiling.
'The men, Captain,' I cried, 'where are the others? Are they alive? Have they been killed?'
'Ae laa,' said the captain, smiling and shaking his head. 'Ae laa. Yes, yes, yes.'
– official report from Third Officer Ravi, vessel White Hawk

No one from the Collective has made landfall on Ae Laa since.