Archaeological evidence has established the earliest-known production of wine from fermenting grapes during the late Neolithic or early Chalcolithic in the Caucasus and the northern edge of the Middle East. An extensive gene-mapping project in 2006 analyzed the heritage of more than 110 modern grape cultivars, narrowing their origin to a region of Georgia. This matches the earliest discovered sites containing shards of wine-stained pottery, dated to c. 6000 BC in Georgia, and c. 5000 BC in Iran. The jars at the northwestern Iranian site already showed treatment with preservative turpentine pine resin, the flavoring of modern retsina. By c. 4500 BC, wine production had spread to Grecian Macedonia, the site of the first recovered crushed grapes, and an entire winery was discovered in 2011 in