In 1992, the discovery chemical evidence of 5000-year-old beer found at Godin Tepe in the Zagros mountains of Iran was reported in the journal Nature. Beer was the preferred fermented beverage of the ancient Sumerians. Chemical evidence was found from an organic residue inside a pottery vessel that had apparently been used for beer fermentation or storage. Some grooves were found inside the double-handled jar which contained a pale yellowish residue that gave a positive test for oxalate ion. Calcium oxalate, only slightly water-soluble is a principal component of sediment that settles from barley beer. In 1991, evidence for the earliest grape wine of had been found in the same area, and to be of similar age, about 3500 - 3100 BC.[Image: Wine jar about 3000 BC from Godin Tepe]