Umbrian was the language of Sabellic populations in central Italy, including Umbria (see Umbrians) and neighbouring areas to the south that were occupied by the Volsci, Marsi, and Sabini. The bulk of scholarly knowledge of Umbrian comes from the Iguvine Tables (see fig. 1 and TABULAE IGUVINAE).The remaining material consists of about fifty mostly very short inscriptions from the 7th through the 1st centuries bce. A Volscian lex sacra of several lines, found at Velletri but probably stemming from elsewhere, is also noteworthy, as is the extreme age of the so-called Paleo-Umbrian material mostly from the 7th century.Umbrian is distinguished from Oscan, probably its closest relative, by many phonological developments that have, in their aggregate, generally obscured the resemblance of its vocabulary to cognates elsewhere in Italic. Many consonant clusters were simplified; s was rhotacized to r both between vowels and, by the later period, also word-finally after a vowel; diphthongs were monophthongized; intervocalic d was rhotacized to a sound written rs or ř; and initial l- became v-.