The rhymed and highly stylized poetry of the troubadours,
                         with its allegiance to music, the codes of the courts of love,
                         the Hispano-Arabic assimilation of the philosophy of
                         classical Greece, were essentials of the great Provençal
                         civilization of the twelfth and early thirteenth centuries. The
                         secular splendor of that culture and its relative indifference
                         to the tedious imperium of the Church were in the end
                         (1209) barbarously and viciously ruined by the wave of
                         political ruthlessness and deadly self-righteousness known
                         as the Albigensian Crusade, one of the great atrocities of
                         European history. (It was a bishop, Arnaud de C”teaux,
                         who gave the order, at the sack of Beziers, "Kill them all.
                         God will know His own." And they did.) Both that rich,
                         generous, brilliant tradition and the devastation that had
                         been visited upon it were part of Dante's heritage. The
                         latter had taken place less than half a century before he
                         was born; the Mantuan poet Sordello, for one, had spent a
                         major part of his life at the court of Toulouse. The legacy of
                         the troubadours survived even beyond Dante. Petrarch is
                         sometimes described as the last of the troubadours. And
                         the attention given to the manners, the psychic states, the
                         perspectives, the ultimate power of love, the exalted
                         beloved, the forms of verse, including rhyme, all come from
                         the culture of Provence either directly or via the court of
                         Frederick II of Sicily. 

- Purgatorio
http://www.randomhouse.com/knopf/borzoi/2000springv2/merwin/

A significant literary influence was exercised by the court of the emperor
Frederick II [1212(20)á á50] in Sicily. The emperor himself probably wrote poetry
and had at his court a number of poets. From this circle there developed forms
that were to set the pattern for Italian lyric poetry. One of these forms was
the sonnet, which was to have not merely an Italian but an international
importance. The sonnet is normally a fourteen-line poem, divided into an eight-
line section (or octave) followed by a six-line conclusion (or sestet).<p>

- Italian Vernacular Literature
http://raven.cc.ukans.edu/~hisite/gilbert/06

The sonnet was invented in the early 13th century at the Sicilian court (1208-1250) of the Holy Roman Emperor Frederick II, a multi-lingual monarch of Norman descent. It was based on a Provençal troubadour form taken over into Italian as a canso or canzone. This was a long poem, made of up stanzas which divided in two parts (sometimes unequal), each of which could also be broken into two sections. The two main sections of the stanza form, the fronte and sirma, were separated by a volta ("turn"). This was a song form--parallel with the A-A-Bridge-A pattern of the 32-bar American popular song.
The sonnet form is a "prescribed" form made by fixing the length and character of this stanza form. Of the 125 poems surviving from Frederick's court, 35 are sonnets, 25 by one lawyer, Giacomo da Lentino. These are 14 lines of 11-syllables with an octave always rhyming abababab, 24 with 2 new rhymes after the turn into the sestet, and 24 dealing with Love.
- Origins of the Sonnet
www.uwp.edu/academic/english/canary/sonnet_origin.html 

DANTE IS HEIR to a complex and lively Italian lyric tradition that
                         had its roots in the Provencal poetry nourished by the rivalling
                         courts of twelfth-century southern France. The conventions of
                         troubadour love poetry - based on the notion of the lover's feudal
                         service to "midons" (Italian "madonna"), his lady, from whom he
                         expects a "guerdon" (Italian "guiderdone"), or reward - were
                         successfully transplanted to the court of Frederick II in Palermo,
                         which became the capital of the first group of Italian vernacular
                         lyric poets, the so-called Sicilian School; 
                         The "leader" (or "caposcuola") of the Sicilian
                         School was Giacomo da Lentini, most likely the inventor of the
                         sonnet (while the Provencal canso was the model for the Italian
                         canzone, the sonnet is an Italian, and specifically Sicilian,
                         contribution to the various European lyric "genres"). Giacomo
                         signs himself "the Notary," referring to his position in the
                         imperial government; 
 Like
                         Giacomo, the other Sicilian poets were in the main court
                         functionaries: in the De vulgari eloquentia Guido delle Colonne is
                         called "Judge of Messina," while Pier della Vigna, whom Dante
                         places among the suicides in Hell, was Frederick's chancellor
                         and private secretary. Their moment in history coincides with
                         Frederick's moment, and the demise of their school essentially
                         coincides with the emperor's death in 1250

Dante and the lyric past
http://dante.ilt.columbia.edu/new/library/cambridge/cambridge_ch02.html