Most of the poets' dates are uncertain, and therefore only an approximate chronological arrangement can be attempted, with the following rough groupings of poets who make use of exemplary comparisons: poets of the twelfth century; those writing at the turn of the twelfth and thirteenth centuries; those whose poetic activity extends into the first decades of the thirteenth century; those falling entirely within the thirteenth century. Those poets writing in the twelfth century begin (in approximate chronological order) with Marcabru and include Rigaut de Berbezilh, Raimbaut d'Orange, Bernart de Ventadorn, Raimon Jordan, Arnaut de Mareuil, Arnaut Daniel, Bertran de Born, Folquet de Marseille, Guiraut de Bornelh, Garin d'Apchier, Guiraut de Salinhac and Guiraudo lo Ros. Those twelfth-century poets whose poetic activity extends into the early years of the thirteenth century include Gaucelm Faidit, Peire Vidal,Guillem Magret, Raimbaut de Vaqueiras, perhaps also La Comtessa de Dia, and Uc de la Bacalaria (but the dating of these two poets is very uncertain). Poets active in the first two decades of the thirteenth century are: Peirol, Peire Ramon de Tolosa, Guilhem Adémar, Raimon de Miraval, Aimeric de Peguilhan, Elias de Barjols, Pons de Capduelh, and Guiraut de Calanso. Poets writing in the later thirteenth century are: Falquet de Romans, Aimeric de Belenoi, Azalais d'Altier, Paulet de Marselha and Peire Cardenal. This group also includes the two Italian troubadours Bonifacio Calvo and Bartolomeo Zorzi, and the two Catalan troubadours Cerverí de Girona and Guilhem Raimon de Gironela, all of whom adopted the langue d'oc, the language of the troubadours, as their linguistic medium.