early form of Galician-Portuguese was already spoken in the Kingdom of the Suebi and by the year 800 Galician-Portuguese had already become the vernacular of northwestern Iberia. The first known phonetic changes in Vulgar Latin, which began the evolution to Galician-Portuguese, took place during the rule of the Germanic groups, the Suebi (411–585) and Visigoths (585–711). The Galician-Portuguese "inflected infinitive" (or "personal infinitive") and the nasal vowels may have evolved under the influence of local Celtic (as in Old French). The nasal vowels would thus be a phonologic characteristic of the Vulgar Latin spoken in Roman Gallaecia, but they are not attested in writing until after the 6th and 7th centuries. Vowels Like Catalan and German, Portuguese uses vowel quality to contrast stressed syllables with unstressed syllables. Unstressed isolated vowels tend to be raised and sometimes centralized. Consonants Phonetic notes Semivowels contrast with unstressed high vowels in verbal conjugation, as in (eu) rio and (ele) riu . Phonologists discuss whether their nature is vowel or consonant. In most of Brazil and Angola, the consonant hereafter denoted as is realized as a nasal palatal approximant , which nasalizes the vowel that precedes it: . proposes that Portuguese possesses labio-velar stops and as additional phonemes rather than sequences of a velar stop and . The consonant hereafter denoted as has a variety of realizations depending on dialect. In Europe, it is typically a uvular trill ; however, a pronunciation as a voiced uvular fricative may be becoming dominant in urban areas. There is also a realization as a voiceless uvular fricative , and the original pronunciation as an alveolar trill also remains very common in various dialects. A common realization of the word-initial in the Lisbon accent is a voiced uvular fricative trill . In Brazil, can be velar, uvular, or glottal and may be voiceless unless between voiced sounds. It is usually pronounced as a voiceless velar fricative , a voiceless glottal fricative or voiceless uvular fricative . See also Guttural R in Portuguese. and are normally , as in English. However, a number of dialects in northern Portugal pronounce and as apico-alveolar sibilants (sounding somewhat like a soft or ), as in the Romance languages of northern Iberia. A very few northeastern Portugal dialects still maintain the medieval distinction between apical and laminal sibilants (written s/ss and c/ç/z, respectively). As a phoneme, occurs only in loanwords, with a tendency for