Bookland is a fictitious country created in the 1980s in order to reserve a Unique Country Code (UCC) prefix for EAN identifiers of published books, regardless of country of origin, so that the EAN space can catalog books by ISBN rather than maintaining a redundant parallel numbering system.
From the creation of the ISBN until January 1, 2007, the ISBN was a 9-digit number followed by a modulo 11 checksum character that was either a decimal digit or the letter X. A Bookland EAN was generated by concatenating the Bookland "Unique Country Code" 978, the digits of the book's ISBN other than the checksum, and a checksum digit (computed now with a modulo 10 like other EAN numbers).
Since parts of the 10-character ISBN space are nearly full, all books published from 2007 on are expected to use the 13-digit ISBN, which is identical to the Bookland EAN. Books numbered with prefixes other than the initial 978 will not be mappable to 10-character ISBNs. At least one new "Universal country code" (979) has been assigned in EAN-13 to Bookland for its expansion. The first use of this UCC code has been allocated by ISBN for publishers in the French language, which can use now the additional prefix "979-10-" in addition to the nearly full "978-2-" prefix (onto which legacy ISBN-10 numbers starting by "2-" have been remapped).
The "Unique Country Code" 977 is used in a similar fashion to create an EAN number out of an ISSN.
The term Bookland is deprecated, because the two existing UCC codes used within the international ISBN standard are now officially registered for allocation by the International ISBN Agency (which maintains the official international registry of ISBN numbers allocated to books publishers), and also because the ISO technical committee (that maintains the new EAN international standard) has also allowed the registration of UCC prefixes for use by international organizations or within other international standards, and not just countries (through their national registration agencies).