Finally!

     The palace was a rotten tooth protruding from the desert's ragged
mandible, its torn brown outline the last incisor in a gaping, 
blue-roofed maw.

One almost has to read this sentence aloud, slowly.  The
way you shift back and forth between one- and two- syllable, harsh
sounding words (especially with a 't' sound) and polysyllabic,
software words (e.g., mandible, incisor) makes this sentence very
difficult to speed-read.

... giving them a focus and a unity unknown to the neighbouring
Hordes.

Hmmm... 665 C.E., Qinghai.  Too late for Huns, much too early
for Mongols.  Generic steppe warriors?  If I remember right, this
coincides with one of China's most expansive periods, under the
Tang.  The lowland corridor just north of Qinghai, into Xinhuang,
was firmly in Chinese hands, separating Qinghai from the steppes.
Is this during the period of agressive, expansionistic Tibet?

     That's what SHE was there for.  Water without a pit, an embodied
dakini that was one with the pools...

Let's see... (quickly rereads prefaces to parts 1 & 2)
in 647, the Emperor resurrected a consort, binding her with a
Fierce Protector.  In 653, he and his Empress made his son a
consort from a tiger. Now, 12 years later, he's a joke and the
Empress, who holds all the reins, is exiled.

It's clear that the Empress, Wu Lin, is superhuman, but nothing
else seems clear.

                         W A T E R F A L L S
                       
                               a mystery

...and it's still not clear why it's billed as a mystery, though
there are lots of mysterious goings-on...

hour - her skin already began to tighten, and there was still so much
to do...

I'm guessing that the "skin tightening" is a weakness, perhaps the
wearing off of whatever she uses to postpone aging.

a moment she considered spending some of her precious power in 
annihilating him for the affront--

So her power has limits...

     And then, she laughed, with her temple wind-chime voice.  Why had
she never seen jesters like this one, before?  That's what he'd be for
her, once... once...  

Happosai as just a jester?  An unnerving thought...

     "Hurry up," Akane replied flatly.  

Very unlike Akane to respond "flatly".  Perhaps there's a reason?

     "Go away, Mr. Saotome," Akane said commandingly.
     
     To Ranma's surprise, his Pop turned and almost hurried down the
stairs, without even a farewell sign.

     "You go away too, Ranma," she continued, turning her gaze to him.
"I've got to go to school tomorrow, and I don't really feel like
dealing with you right now.  I'm too tired."

     Ranma opened his mouth, closed it, and left her room.

VERY interesting...  has Akane developed the Bene Gesserit Voice?

     "A meeting, Master of Pools?"

An auxiliary title for Musk rulers, I see...

     As the customers began to shout louder, Mousse tried his hardest 
not to break down and cry.

An effective way to break up the foreboding real plot development,
but it might have been even more effective if made a bit funnier.

     "Who am I kidding?" she said quietly.  She had been dreaming
about him last night; he had woken her up in the middle, so the memory
was still vivid.  She had been a princess trapped in a tower, kept
prisoner by an evil witch who bore a close resemblance to Shampoo.
The witch had two helpers, who looked quite a bit like Ukyou and
Kodachi, except not quite as pretty.  All three of them had used all
their wiles to try to seduce the handsome prince who came to rescue
her, and...

     And then Ranma, the stupid jerk, had woken her up.

Very similar to one of the scene's from the manga's "Akane's dream"
story.  It rings true as the sort of of dream which would obsess
Akane repeatedly, but she should remember having had it before.

It's not completely clear from the description given if Akane is
consciously aware that Ranma is the prince.

     Don't be afraid, she told herself.  Ranma is right outside; if
you scream, he'll hear you.

This is certainly Akane, to think this moments after thinking he's
a jerk...

     "Get OFF me!"

     And he did.  He dropped like a burnt leech, and scuttled back
from her.

Hmmm... more evidence that something has happened to Akane, or
at least her voice...

     Akane reached out with her hand and brushed the flies away.  And
they _burned_, burned like torches to her eye, and...

...and is the missing end of that sentence significant?  "..and
they awakened her (memories | powers | potential)."

     "The pit," he said quickly, "down in the..."

     A dry hiss cut off his next words.  She saw the skin of his face
ripple.

Was Happosai throwing it off, and about to reveal something
IMPORTANT?  And was suddenly murdered in consequence?

 He clawed ...
until she screamed at him to stop, and he did, ...

...more evidence...

     "Finest Musk teddy bear wrapping paper." The Amazon cocked what
remained of an eyebrow.  Herb bowed.  "AND a red ribbon."

That wacky Herb!

     Mousse sighed, and licked a dribble of blood from his lips.
     
     "Shampoo is gone," he said.

So was Tarou sent to fetch Shampoo?  Rouge seemed more likely at
the time the order was given.  But, by the end of this episode,
Akane seems more likely to be the one the order _should_ have
meant.

     "Free at last!" Genma cried, embracing Soun.  "Our years of
prayer have paid off...  Praise the gods!"

     "How we have waited for this day!" Soun sobbed, as he hugged
Genma back.

Right IC...

     "Pop, Mr. Tendo, stop it!" Ranma snapped.  "He's dead.  It's not
funny.  It ain't right to celebrate when somebody dies, no matter how
much ya hate 'em!  This ain't the time or the place!"

and Ranma is IC, nicely done...

     "I wish they were not so insensitive," Nodoka said quietly.  "I
remember the Master well from when Genma was courting me.  He was a
most manly man, though he perhaps took it too far, if such a thing can
be done."

Certainly consistent with the manga Nodoka, though uninterestingly
so, except as light comic relief...

     Akane said nothing,

After all, what might happen if she did?

If I didn't know better, I would say that his blood
has been replaced with water.  Though how that could happen, I cannot
say in my capacity as a medical man."

Perhaps some symbolic or mystical meaning for the swap?

     He laughed again.  Ranma stared at him in open-mouthed disgust.

Not clear why Ranma reacts quite this way.  He's seen Tofu around
Kasumi before.  Sad horror, perhaps?

     And she was, perhaps, the loveliest woman that Ranma had ever
seen.  Her figure was perfection; looking at her made it hard to
breathe, hard to think.  A mild buzzing began to emanate from the
centre of his skull.  The woman smiled at him; the buzzing grew.
Black specks...

Presumably this is Wu Lin...

     Akane stepped between him and the woman, and the noises ceased.

_VERY_ interesting...  (The final signs have been fulfilled, and
the Eternal Akane summoned forth to do battle once more...)

     Ranma watched, enraptured.  Dimly, he realized that he should be
getting ready to fight; whoever the woman was, she was obviously
dangerous.  But she was so beautiful...

Again, very unnerving...

     "Who are you?" Akane asked again.

     "Never shall you know my name, little child," the woman said.
The serpent-fangs distorted her mouth and voice, but it was still
almost unbearably sweet and seductive.  Even from here, Ranma could
see that her tongue was forked.  "For I shall kill you before granting
you even that much of an increase in your power."

So she knows something about the power Akane now wields...


Well, another exquisite chapter.  You've apparently cut back on
the "strange, impressionistic, stream-of-consciousness writing"
style (your own words), which, IMHO, is a plus.

The gap in time between parts 1 & 2, and this one, will probably
lose you readers.  This is very tightly interwoven, and I had to go
back and reread carefully to figure out what was going on here.

I'm still eager to find out where you're going.