Boundaries of Wilderland
 

In LOTR the Emyn Muil is stated to be "the southern march of Wilderland".

If the Misty Mountains were Wilderland's western boundary, does that mean that Lorien, the Field of Celebrant, Fangorn Forest and the Wold of Rohan were all within Wilderland too ?

I was thinking the Anduin was the western boundary, but I could be mistaken.

Looking at the fold-out map at the back of "FotR," it's difficult if not impossible to say where the western border actually lies. If there must be a specific border, I would consider it to follow the Misty Mountains down to their southern end and then include everything east of the River Entwash (including half of Rohan) and everything north of Cair Andros (including northern Ithilien) and then all along the north of the Ered Lithui. This would mean that both Moria and Lorien were included in "Wilderland." Some people may take issue with that, but I never did.

Wilderland is the Westron version of the Sindarin name of Rhovanion and a name genarally given to the lands between the Misty Mountains and the River Celduin (Running)....(Foster's Guide to Middle-earth). Its bounderies were approximate, but included The Misty Mountains, The River Celduin-Carnen and the Grey Mountains (Tyler's Tolkien Companion). Hobbit name for the lands beyond the Misty Mountains, [in] E[lvish i.e Sindarin] Rhovanion [sic], but often used to include the wild lands on the west side of the range, that is Eastern Eriador (A Readers Companion- Hammond and Scull). I think it basically means what you see in the map reproduced in The Hobbit, however this has some of it missing. I have always thought of Dorwinion as part of Wilderland and certainly Dol Guldur. These are in the Southern part of the map. If you draw a line across the map south of Dol Guldur and north of The Emyn Muil most of Rohan is below it (apart from the Wold), however Lorien is in the area and so is half of Fangorn. I respectfully suggest that these being Independent of the region, they should not be included, as being enclaves or parts of other sovereign nations.

Is Wilderland actually a country and not just a geographic area? I always thought that Wilderland was just a term describing the area, much like I would call the section of the U.S. I live in the Midwest. The Midwest is not a political boundry but simply a way to describe where things are. Much like I'd say "I live in Indiana which is in the Midwest, I thought people in M-E might say "Lorien is in the Wilderland."

You are correct in that 'Wilderland' was simply used to describe the entire region.
What narfforc was saying was that Lórien and Fangron were separate, sovereign states and thus should be considered to be apart. But then, the same could be said for Thranduil's realm in Mirkwood, could it not?

Rhovanion (Wilderland) had once been the realm of Vidugavia, the self styled King of Rhovanion. The Eotheod were the remnants of The Northmen, who had formerly been a numerous and powerful confederation of peoples living in the wide plains between Mirkwood and the River Running, great breeders of horse and riders renowned for their skill and endurance, though their settled homes were in the eaves of the Forest, and especially in the East Bight, which had largely been made by their felling of trees. Later their lands lay north of Mirkwood, between the Misty Mountains westward and the Forest River eastwards. Southward it extended to the confluence of the two short rivers that they named Greylin and Langwell. So Rhovanion had been occupied by The Northmen (The Eotheod) and The Wainriders at seperate times and later The Balcoth. These events happened during the Third Age, both Lorien and The Woodland Realm were founded during the Second Age therefore sovereign states before this time, as for Fangorn it was ageless in human terms. Lorien was formerly the Nandorin realm of Lorinand, people by those elves who forsook The Great Journey in the First Age. It extended into the forest on both sides of The Great River, including the region where afterwards was Dol Guldur.

Rhovannian is a region
 

...like Eriador on the other side of the Misty Mountains or the lost Beleriand, these included the sovereign nations within them like Arnor and Eregion withing Eriador.