Which of the nations/provinces of Tamriel would you expect to be overall the poorest, least economically advanced of all?

I'm assuming Black Marsh, since we know nothing of it's major exports or natural resources save a few things the empire exploited out of it. I get the idea that that's because it HAS no real economic power.

I would guess Black Marsh as wellm Unless the Hist is willing to give them their sap to export. Though I do see the province's main export being fish.

As of the events of Skyrim, I'd say Morrowind, due to the eruption of Red Mountain and the migration of its citizens to bordering provinces.

Oh, good point! Plus, Black Marsh must he doing much better at this point as they were able to invade Morrowind.

I think I remember hearing about Black Marsh exporting two commodities out of gold, timber and ivory, I assume Valenwood doesn't generate much gold. Plus what Rotavator said.

I think Morrowind could be a potential candidate after the eruption and argonian invasion. The tidbits of info in TESV makes it sound like Morrowind is little more than a rugged wasteland at this point.

Oh, good point! Plus, Black Marsh must he doing much better at this point as they were able to invade Morrowind.