May originally have been called Purdeighsland and represented one of the few places that idiot explorer Sir Roderick Purdeigh actually found rather than just looked for.
On the Discworld Mapp, it has a suspiciously Tasmania-like relationship to the continent of Fourecks. Tasmania was originally called Van Diemen's Land after its Dutch discoverer and kept this name in popular song lamenting transportation to the penal colony there, even after an Englishman called Tasman became its governor. Cf. the traditional ballad only to be sung after the sixth pint of Guinness, The Black Velvet Band, in which a naive young Belfast lad is inveigled into crime by a scheming wench, caught by the bloody Brits, and transported to Van Diemen's Land. No doubt Ankh-Morpork has an equivalent song.