Although the first instances of coherent Basque phrases and sentences go as far back as the San Millán glosses of around 950, the large-scale damage done by periods of great instability and warfare, such as the clan wars of the Middle Ages, the Carlist Wars and the Spanish Civil War, led to the scarcity of written material predating the 16th century. Although the first instances of coherent Basque phrases and sentences go as far back as the San Millán glosses of around 950, the large-scale damage done by periods of great instability and warfare, such as the clan wars of the Middle Ages, the Carlist Wars and the Spanish Civil War, led to the scarcity of written material predating the 16th century. The earliest surviving traces of Basque literary activity go back to the 16th century, but significant production does not seem to have set in until the 17th century. Since the end of the Francoist period in Spain, the formation of a standard language, and the large scale introduction of Basque into the education system consequently increased literary activity. While much of the literature written in Basque remains targeted at the native audience, some works by Basque authors have been translated into other languages, such as Bernardo Atxaga, and achieved global recognition. A few songs from the 16th century have survived, such as the Song of the Battle of Beotibar that deals with the battle fought in 1321 and a group of verses known as The Burning of Mondragón from the time of the Basque Clan Wars. The earliest piece of prose written in Basque is a letter composed in 1537 by the Biscayan Juan de Zumárraga from Durango, the first bishop of Mexico. Only a few years later in 1545, the first book known to have been put into print is published - a collection of poems fashioned by Bernard Etxepare, a priest from Lower Navarre in the Northern Basque Country, by the title Linguæ Vasconum Primitiæ ('Beginnings of the Basque Language'). In this book, Etxepare expresses his hopes that the first publication of a book in Basque will serve to invigorate the language and culture. His efforts were undoubtedly influenced by wider movements in Europe at the time that encouraged literary production in vernacular languages rather than Latin. The next publication is a recently discovered pastoral play by Joan Perez de Lazarraga (1548?—1605) by the name of Silbero, Silbia, Doristeo and Sirena produced between 1564 and 1567 in Larrea, Alava, making it the earliest surviving play in Basque. With 102 pages (some damaged) it is also the longest early text. 1571 saw the publication of Joanes Leizarraga's New Testament translation into a standardised form of his Lapurdian dialect, promoted by Jeanne d'Albret, Queen of Navarre. He also wrote a small number of other religious works. The closing years of the 16th century see another publication, this time from the South, of a collection of proverbs written in the Biscayan dialect called Refranes y sentencias by an unknown author. However, by this time, the centre of Basque literary production had firmly established itself to the north of the Pyrenees, in Lower Navarre and the French provinces of Labourd and Soule, where it would remain for several centuries. Although dialectal differences are clearly visible in these early texts, it is also clear that the differences in the 16th century were considerably smaller than they are today.