The southern and principally Italian-speaking half of Italy's central alpine region of Trentino-Alto Adige. Trento is the regional capital. Viticulture is centred on the valley of the Adige and the hills immediately to the east and west of the river, with an occasional excursion to side valleys such as the Valle dei Laghi and the Val di Cembra. The terrain further east and west into the Dolomites and the Gruppo di Brenta mountains is too rugged and mountainous for viticulture. Although the region is far to Italy's north, and Trento is on the 46^th degree of latitude, the climate is not necessarily cool, as heat rapidly builds up at lower altitudes during the summer months . Viticulture is therefore by no means confined to early-ripening vine varieties. Annual average regional production has fallen from over 1 million hl to 700,000 hl/18.5 million gal. More than 70 per cent of the vineyards are registered for DOC wine production, a proportion second only to Alto Adige in Italy.
—Oxford Companion To Wine