Saruman's economic infrastructure unexplained?

[Tuor of Gondolin]

I believe somewhere (in Letters?) Tolkien makes
observations regarding sauron's slave-tended fields in Nurn
something to the effect that even a tyrant needs an
economic infrastructure to support his policies. And it seems
that other areas, including Gondor, Rohan, Hobbiton, Lorien,
Laketown, the Beornings, etc., all have either an implicit or
explicit economic infrastructure. The exception seems to be
Saruman. Are there any suggestions or deductions as to how
he could support a 10,000 + army and some hundreds of auxiliaries,
such as wargs and the nonfighting elements needed to supply
them? After all, he controlled a fairly constrained area, the
Dunlendings don't seem to be more then a subsistence economy.
And he was hemmed in by Fangorn, Rohan, and the virtually desert
areas of Enedwaith. You can see how Sauron could draw on his
slave fields and tribute from east and south, Gondor on its outlying
areas, including the Pelennor Fields and South Gondor. But where
was Saruman's economic basis for power?

[Lindolirian]

I see what you mean. Isengard may have been a large and lavish Numenorean outpost, but it was still only that, an outpost. However, one has to remember that Saruman had many underground operations going on. He could have been mining in the Misty Mts. to the north or keeping barracks of Orcs under Nan Curunir. But still, all this was still probably not enough. My guess was that he was very deep in debt to Sauron who "loaned" him orcs and resources in an effort to build up his ally. Saruman seemed very unstable and his only option for survival was to spread over Rohan, not only for war in service to Sauron, but to be able to sustain himself.

[Hot, crispy nice hobbit]

This sounds interesting...

I had always assumed that Saruman just "leased" some of the lands from King Theoden via Grima; just like how Grima borrowed Theoden's sword (many other things that men missed).

To be exact, however, Saruman was said to have started fortifying Isengard in 2953... which gave him 64 years to give birth to 10,000 Uruk-hai, build foundaries and furnaces within the ring of Isengard, persuade the Dunlendings to join his cause, and tutor Grima in the ways of clever speech... All out of sight from stragglers.

Saruman must have had some deep underground laboratories underneath the Misty Mountains...

[Maerbenn]

Originally Posted by Hot, crispy nice hobbit

Saruman was said to have started fortifying Isengard in 2953... which gave him 64 years to give birth to 10,000 Uruk-hai

From note 7 (an Author’s note) to ‘The Palantíri’ in Unfinished Tales:

The [White] Council seems to have been unaware, since for many years Isengard had been closely guarded, of what went on within its Ring. The use, and possibly special breeding, of Orcs was kept secret, and cannot have begun much before 2990 at earliest. The Orc-troops seem never to have been used beyond the territory of Isengard before the attack on Rohan. Had the Council known of this they would, of course, at once have realized that Saruman had become evil.

[Eomer of the Rohirrim]

He got really busy and inventive. Plus, he was a powerful wizard.

[Kuruharan]

Here is a thread that in some ways relates to this topic.

[Tuor of Gondolin]

Interesting comments, particularly Saruman's time limitations
and the suggestion (serious?) of a Sauron subsidy and
assistance, as is the related link.

How about this as a possible way of Saruman's
skirting around his economic/geographic limitations:

Even taking into account Gandalf's observation:

But Isengard cannot fight Mordor, unless Saruman first obtains the Ring.

What if Saruman had been successful in not destroying Rohan but
rather in using Theoden and Wormtongue to forge an alliance (with
himself, of course, as dominant figure---think Hitler vis-a-vis Mussolini
in relative power). With this de facto grouping he could very well have
also alligned with the realpolitik Steward of Gondor. If you posit the
Ring remaining lost wouldn't this military/economic bloc, with a
neutral Lorien blocking Sauron efforts to flank it, have been capable
of at least holding the east side of the Anduin? Then Rhovannion might
have become the disputed region of these power blocs. And while
orcs and Gondor/Rohan fighting together seems odd, recall the
U.S.S.R. and U.S.A./U.K. alliance in World War II. Mordor would have the
bigger numbers + oliphaunts, but the western group would have
superior cavalry plus Saruman's technology, including blasting powder.
Oh yes, and you have Gandalf, Elrond, dwarves, and Beornings and
Laketowners causing mischief in the north.

Just a thought.