Lore

[Sniper4]

According to The Infernal City...

http://www.imperial-library.info/content...lore-notes

The Argonians control Morrowind, and associate some sort of ritual with the crater of Vivec, now called the Scathing Bay. p.259

So they still control it, apparently. Just to what degree?

Also, from Lord of Souls...

The An-Xileel “stopped their advance [in Morrowind] decades ago, and haven’t showed the slightest interest in doing anything since then.” They have, however, prevented the Empire from reclaiming that territory.

In order to keep the empire out, they have to have forces stationed in the province.

Perhaps:
-The garrison in Silgrad Tower is one meant to keep Imperial forces out of the province.
-To maintain the garrison, feed their soldiers, and mine materials, they have enslaved the local Dunmer.

How does that sound?

edit: In other words, they'd still be a part of the main Hist Argonians, but they simply have a rather brutal way of maintaining their army .

edit 2: I'm imagining a fairly decentralized Argonian leadership in Morrowind. Perhaps they don't even govern most of the cities, but demand tribute from time to time to maintain their garrisons?