The beginnings of the Italian vernacular lyric can be traced to the so-called Sicilian school of poets gathered at the court of the emperor Frederick II at Palermo, approximately during the period 1230–1250. There is thus a considerable time-lag between the initial development of the Italian lyric in the vernacular and the troubadour lyric, on which it is based. This is in part a parallel to the chronological gap between the troubadour and trouvère lyric, but it is here much greater in extent. From about the end of the twelfth century, the troubadour lyric had become very widely known and imitated, and its overriding prestige and authority ensured the spread of its influence to Northern France, to German linguistic areas (where knowledge of itwas, however, mainly transmitted indirectly via the trouvère lyric), and to Spain, but more particularly to Northern Italy, where from the end of the twelfth century the troubadour lyric was cultivated at the courts of powerful patrons. At first, Italian poets wrote poems not merely imitating troubadour poetry, but using the language of the troubadours as their medium. As Jensen points out, these developments were facilitated by the fact that the dialects of Southern France and Northern Italy were closely related and therefore mutually comprehensible. This assiduous cultivation of the troubadour lyric also resulted in the compilation of a large number of collective manuscripts of troubadour poetry in Northern Italy, many still in Italian libraries today.