Within the context of Western music tradition the term is usually used in reference to music of the late Middle Ages and Renaissance. Baroque forms such as the fugue which might be called polyphonic are usually described instead as contrapuntal. Also, as opposed to the species terminology of counterpoint, polyphony was generally either "pitch-against-pitch" / "point-against-point" or "sustained-pitch" in one part with melismas of varying lengths in another (van der Werf, 1997). In all cases the conception was likely what Margaret Bent (1999) calls "dyadic counterpoint", with each part being written generally against one other part, with all parts modified if needed in the end. This point-against-point conception is opposed to "successive composition", where voices were written in an order with each new voice fitting into the whole so far constructed, which was previously assumed.
Although the exact origins of polyphony in the Western church traditions are unknown, the treatises Musica enchiriadis and Schola enchiriadis, both dating from ca. 900, are usually considered the oldest extant written examples of polyphony. These treatises provided examples of two-voice note-against-note embellishments of chants using parallel octaves, fifths, and fourths. Rather than being fixed works, they indicated ways of improvising polyphony during performance. The Winchester Troper, from c. 1000, is the oldest extant example of notated polyphony for chant performance, although the notation does not indicate precise pitch levels or durations.
Traditional (non-professional) polyphony has a wide, if uneven distribution among the peoples of the world. Most polyphonic regions of the world are sub-Saharan Africa, Europe and Oceania. It is believed that origins of polyphony in traditional music vastly predates the emergence of polyphony in European professional music. Currently there are two contradicting approaches to the problem of the origins of vocal polyphony: Cultural Model, and Evolutionary Model. According to the Cultural Model, origins of polyphony are connected to the development of human musical culture; polyphony came as the natural development of the primordial monophonic singing; therefore polyphonic traditions are bound to replace gradually monophonic traditions. According to the Evolutionary Model, origins of polyphonic singing are much deeper, and are connected to the earlier stages of human evolution; polyphony was an important part of a defence system of the hominids, and traditions of polyphony are gradually disappearing all over the world.
European polyphony rose out of melismatic organum, the earliest harmonization of the chant. Twelfth century composers, such as Léonin and Pérotin developed the organum that was introduced centuries earlier, and also added a third and fourth voice to the now homophonic chant. In the thirteenth century, the chant-based tenor was becoming altered, fragmented, and hidden beneath secular tunes, obscuring the sacred texts as composers continued to play with this new invention called polyphony. The lyrics of love poems might be sung above sacred texts in the form of a trope, or the sacred text might be placed within a familiar secular melody.
These musical innovations appeared in a greater context of societal change. After the first millennium, European monks decided to start translating the works of Greek philosophers into the vernacular, following in the footsteps of the Muslims who did that 500 years earlier. Western Europeans were aware of Plato, Socrates, and Hippocrates during the Middle Ages. However they had largely lost touch with the content of their surviving works because the use of Greek as a living language was restricted to the lands of the Eastern Roman Empire (Byzantium). The ancient works, as well as Muslim commentaries, started then being translated. Once they were accessible, the philosophies had a great impact on the mind of Western Europe. Faced with new ideas, society was forced to view itself in a different light as secular ideas competed with the doctrine of the Roman church.
This sparked a number of innovations in medicine, science, art, and music.
The oldest surviving piece of six-part music is the English rotaSumer is icumen in (ca. 1240). (Albright, 2004)
European polyphony rose prior to, and during the period of the Western Schism. Avignon, the seat of the antipopes, was a vigorous center of secular music-making, much of which influenced sacred polyphony.
It was not merely polyphony that offended the medieval ears, but the notion of secular music merging with the sacred and making its way into the papal court. It gave church music more of a jocular performance quality removing the solemn worship they were accustomed to. The use of and attitude toward polyphony varied widely in the Avignon court from the beginning to the end of its religious importance in the fourteenth century. Harmony was not only considered frivolous, impious, and lascivious, but an obstruction to the audibility of the words. Instruments, as well as certain modes, were actually forbidden in the church because of their association with secular music and pagan rites. Dissonant clashes of notes give a creepy feeling that was labeled as evil, fueling their argument against polyphony as being the devil’s music. After banishing polyphony from the Liturgy in 1322, Pope John XXII spoke in his 1324 Bull Docta Sanctorum Patrum warning against the unbecoming elements of this musical innovation. Pope Clement VI, however, indulged in it.
Iso-polyphony is a form of traditional Albanian polyphonic music. It can be divided into two major stylistic groups as performed by the Tosks and Labs of southern Albania. The term iso is related to the drone, which accompanies the iso-polyphonic singing. The drone is performed in two ways: among the Tosks, it is always continuous and sung on the syllable ‘e’, using staggered breathing; while among the Labs, the drone is sometimes sung as a rhythmic tone, performed to the text of the song. It can be differentiated between two-, three- and four-voice polyphony. The phenomenon of Albanian folk iso-polyphony is proclaimed by UNESCO as a "Masterpiece of the Oral and Intangible heritage of Humanity". This type of folk vocal tradition is also found in Macedonia and Bulgaria.
Also Georgian polyphonic singing - but it is under threat.