The ancient Nordic concept of the "middle land", or "Middangeard", where mortals live, most famously popularized as...
The continent in JrrTolkien's LordOfTheRings books. -- JustMab
"Middle" because their cultures are between the primitive, wild unharvested lands to the East and South, and the sophisticated lands formerly to the West, Aman, that the Valar (Powers) Maiar (Spirits) and High Eldar (Star-Folk) live in.
Endor consists of Eriador (Empty Land [between Mountains]) in the North, Gondor (Land of Stones) in the South, Rhovanion (East Way) that hobbits call "Wilderland", and Mordor (Black Land) in the southeast. Beyond this is Khand (Scythia) to the East, and Harad (South) in the tropics.
Gondor did not bother to ask the locals the name of their land, and just called it Harad, "South" in their own language. See NamingConqueredLands for some more of this.
The Hobbit's Shire, in Eriador, was originally a suzerainty of a kingdom called Arthedain, the Land of the Kings of Men, a sister state of Gondor.
A map of MiddleEarth can be found here: http://www.taylorcustom.com/localinks/mearth/mearthmap.html
To the West, under the sea, are the ruins of a great sub-continent called Beleriand (Pearl Region). It sank at the end of the First Age, and the crack it folded in on extends through the Lune (Blue) Mountains into Eriador. This formed the Gulf of Lune, where Cirdan (the oldest Elf in LotR) founded the Grey Havens.
-- PhlIp (whose birthday is December 19th, the same day FotR starts in theatres. Coincidence? We think not!) [Although Return was available in these here parts (Chicagoland) 17 Dec -- sorry.]
See LordOfTheRingsPartOne and LordOfTheRingsPartTwo for information on the two movies released thus far. LordOfTheRingsPartThree was released at the end of 2003.
Except Tolkien's Middle Earth, like the Nordic, is supposed to include the East and South.
See also the Tolkien wiki: http://www.thetolkienwiki.org/wiki.cgi