Rye tends to be less finicky than wheat so that it can generate at least some yield even in poorer and more acidic soils, where wheat would not grow. Historically, therefore, rye was the only grain that could be counted on, from the North Sea to the Ural Mountains, to ripen in the short and often rainy summers of central Europe. Rye has been planted with particular success in such countries as Austria, the Czech Republic, Germany, Poland, and Slovakia. These are also the places where rye beers were once prominent.
Rye is mentioned by the Greek historian Hellanicus of Lesbos as being used in beer in Phrygia and Thracia – what is now modern-day western and central Turkey and northern Greece – as early as the 5th century B.C. Able to grow in conditions that may not have been as suitable for barley or wheat, rye may have been a primary grain in early beers, but was certainly an additional ingredient.
Russian kvass and Finnish sahti both have evidence of rye as a principle ingredient – although kvass appears to have been primarily brewed from rye baked into bread. The bread, dried and crumbled, then appears to have been mashed in much the same way as actual grain.
Residue sampled from jars in a Bronze Age grave in northern Italy points to barley, wheat, millet, and rye being used in the production of beer.
As noted above, Tacitus wrote in De origine et situ germanorum “…the Germanii serve an extract of barley and rye as a beverage that is somehow adulterated to resemble wine.”
Much later in the medieval period, circa 1250-1260, the Italian doctor Aldobrandino de Siena wrote in Li Livres pour la Santé et du corps (a medical treatise written for and by order of King Louis IX of France – one of the first written in the vernacular rather than in Latin) that ale made from rye or rye bread with mint and wild celery was the best kind of beer for general health, good skin, and proper gastro-intestinal maintenance.
There is speculation by a number of historical beer and brewing sources that the Reinheitsgebot, or Bavarian Purity Law, of 1516 was less about maintaining the purity of a barley beer and more about preserving the more glutinous grains (e.g. wheat, rye, spelt) for the production of bread following several years of bad grain harvests.,
From northwest Denmark, circa 1500-1300 BC, to the Swedish island of Gotland as late as the first century AD, Nordic peoples were imbibing an alcoholic ‘grog’ or extreme hybrid beverage rich in local ingredients, including honey, bog cranberry, lingonberry, bog myrtle, yarrow, juniper, birch tree resin, and cereals including wheat, barley and/or rye…
Despite its documented presence in ancient beverages, rye is a difficult grain with which to brew. Rye has almost no hull, and is high in gluten. For this reason, there is nothing to prevent rye from becoming a gooey mess in the mash tun that can quickly solidify into a clay-like mess. Ancient texts point to rye as just one of many grains used collectively in the mash, and modern recipes lean towards a grain bill of from 20% to 50% rye blended with wheat and/or barley. Presumably, the barley hulls assist in keeping the mash broken up enough to be able to extract the liquor. One modern craft brewer experimenting with higher percentages of rye malt recommends the use of rice hulls in the mash for this purpose.
 German Beer Institute
 Nelson, chap. 2
 Hornsby (2012), pp. 296-297
 Patterson & Hoelst-Pullen, pg. 12
 Wallis, pg. 189
 Landouzy & Pepin
 German Beer Institute
 McGovern, et al, pg. 1. The biomolecular archaeological evidence provides concrete evidence for an early, widespread, and long-lived Nordic grog tradition with distinctive flavors and probable medicinal purposes. The researchers obtained ancient residue samples from four sites in a 150-mile radius of southern Sweden and Denmark. The oldest, dated 1500-1300 BC, was from Nandrup in northwestern Denmark, where a warrior prince had been buried in an oak coffin with a bronze sword, battle-ax, and pottery jar whose interior was covered with a dark residue. A second Danish sample, dated to a later phase of the Nordic Bronze Age from about 1100-500 BC, came from a pit hoard at Kostræde, southwest of Copenhagen. A brownish residue filling a perforation of a bronze strainer was sampled. A third Danish sample was a dark residue on the interior base of a large bronze bucket from inside a wooden coffin of a 30-year-old woman, dating to the Early Roman Iron Age, about 200 BC, at Juellinge on the island of Lolland, southwest of Kostræde. A reddish-brown residue filling the holes and interior of a strainer-cup provided the fourth sample. Dating to the first century AD, the strainer-cup was excavated from a hoard at Havor on the Swedish island of Gotland in the Baltic Sea. Ancient organic compounds were identified by a combination of chemical techniques: Fourier-transform infrared spectrometry (FT-IR), gas chromatography-mass spectrometry (GC-MS), ultra-high performance liquid chromatography tandem mass spectrometry (LC/MS/MS), and headspace solid phase microextraction (SPME) coupled to GC-MS.
Bernstein, Joshua M. (2010). “Rye Beers: Against the Grain”. Imbibe Liquid Culture. Retrieved 15 January 2017, from http://imbibemagazine.com/rye-beers-against-the-grain.
Cullen, Kevin (2009). “Ale Through the Ages: The Anthropology and Archaeology of Brewing”. The Distant Mirror. Retrieved 14 January, from https://distantmirror.wordpress.com/2009/10/09/ale-through-the-ages-the-anthropology-and-archaeology-of-brewing.
German Beer Institute (n.d.) Retrieved 13 January 2017 from http://www.germanbeerinstitute.com/.
Hornsey, Ian S. (2012). Alcohol and Its Role in the Evolution of Human Society. London: Royal Society of Chemistry.
Hornsey, Ian S. (2003). A History of Beer and Brewing. London: Royal Society of Chemistry.
Landouzy, Louis and Roger Pepin (1911). Le régime du corps de maître Aldebrandin de Sienne. Texte français du XIIIe siècle, publié pour la première fois d’après les manuscrits de la Bibliothèque Nationale et de la Bibliothèque de l’Arsenal. Paris: Champion.
McGovern, Patrick E., Gretchen R. Hall, & Armen Mirzoian (2013). “A biomolecular archaeological approach to ‘Nordic grog.’” Danish Journal of Archaeology, 2:2, 1-20.
McHops, Barley (2010). “When Beer Goes A-Rye”. Beer Culture, Tasting Notes. Retrieved from 17 January 2017, from https://aleheads.com/2010/11/02/when-beer-goes-a-rye.
Nelson, Max (2011). “Beer: Necessity or Luxury?”. Avista Forum Journal of Medical Science, Technology, and Art. 21:1/2, Pennsylvania: Haverford College. pp 73-85.
Patterson, Mark and Nancy Hoalst-Pullen (2014). The Geography of Beer: Regions, Environment, and Societies. New York: Springer.
Wallis, Faith (2010). Medieval Medicine: A Reader. Toronto: University of Toronto Press.