Zoroastrian prayer, the Ashem Vohu, Sogdian MS
The cave at Dunhuang, where this manuscript was found, had probably been sealed up due to threats from either the Tanguts or Karakhanids before excavation. It is the oldest surviving Zoroastrian text and it is written in the Sogdian language. Zoroastrianism, the religion of ancient Iran, was founded by Prophet Zarathushtra and is one of the oldest monotheistic religions. It originated in Central Asia, spreading to Iran where it became the religion of Achaemenid kings and their successors until the Arab conquest in mid-seventh century AD. It continued in Central Asia alongside Buddhism, Manichaeism and Christianity until Islam became the regions’ dominant religion. 
This fragment shows the top 10 lines of the scroll. Also visible at the bottom are traces of where the next sheet would have been attached. The text is large and written in a calligraphic hand. It describes the prophet Zarathushtra meeting an unnamed ‘excellent supreme god’ who dwelt in ‘the fragrant paradise in good thought.’ The main body of the document is written in normal Sogdian language of 8th or 9th century CE. However, the first two lines are truly significant. While at first they were thought to not make sense, the first two lines are actually the Sogdian version of the Ašəm vohū prayer, which were originally composed in Avestan, an ancient Iranian language. 
Ašəm vohū is the second of the four great prayers of the Zoroastrians. The others are Ahuna vairyō (Y. 27.13), Yeŋ́hē hātąm (Y. 27.15), and Airyə′mā išyō (Y. 54.1). The purpose of the Ašəm vohū is to invoke Aša “truth, true word, especially the truth which is represented by the Zoroastrian religion.” It was probably one of the prayers used from the earliest times by the Zoroastrians at the five daily services (times of prayer) they had to observe.
It is possible that this manuscript was written before the Sogdians converted to Zoroastrianism based on certain phonological differences. The word for ‘truth’ is not represented by Avestan ashem of the Sasanian period, nor does a Sogdian equivalent appear to take its place, such as as *rtu or reshtyak. –rtm is used instead, a spelling which is identical to the Achaemenid Old Persian *rtam. Therefore, it can be inferred that the Sogdians knew the prayer through oral transmission before converting to Zoroastrianism. This oral transmission of a sacred text speaks to the importance of earliest prayers and practices of religion by Sogdians.
“Ashem Vohu,” Sacred Texts, British Library. http://www.bl.uk/onlinegallery/sacredtexts/ashem.html
“Ašəm vohū,” Encyclopaedia Iranica. http://www.iranicaonline.org/articles/asem-vohu-the-second-of-the-four-great-prayers
“Zoroastrian Prayer,” British Library. http://www.bl.uk/collection-items/zoroastrian-prayer
Rose, Jenny. I. B. Tauris, 2011. Introductions to Religion: Zoroastrianism : An Introduction. London, GBR: I.B. Tauris.
British Library Or. 8212/84 (ch.00289)
Additional Research Metadata
Discovered in the ‘library cave’ in Dunhuang with 40,000 other texts in 1900 by the Daoist monk Wang Yuanlu who presented manuscripts and paintings to local officials, hoping in return for financial support to pay for conservation work. When the archaeologist and explorer Aurel Stein arrived there in 1907, Wang Yuanlu sold him large numbers of manuscripts and paintings, which are now in the British Library, the British Museum, the Victoria and Albert Museum, and the National Museum Delhi.
A rare Sogd. MS which seems to be Zoroastrian, I.e. belonging to the SogdiansÕ ancestral religion. From line 3 it contans a description of a meeting between Zoroaster and the supreme god, in normal (late) Sogdian. Lines 1-2 contain the text of the holy Zoroastrian ÒAshem vohuÓ prayer, preseved in archaic Old Iranian language. This is by many centuries the oldest surviving MS of any Zoroastrian scripture.
Rose, Jenny. I. B. Tauris Introductions to Religion: Zoroastrianism: An Introduction. London, GBR: I.B. Tauris, 2011