Mosul, where those Genoese halted in 1290 to build their ships, had a tradition of mathematical astronomy and of making fine astronomical instruments – astrolabes and star-globes among them, though a more unusual instrument, dated to the thirteenth century and credited to Mosuli workmanship, was evidently designed to calculate astronomical and geomantic correspondences. It was found in North Africa.
It was in Mosul that al-Tusi, a native of Khorasan, came to study astronomy in 1242. Whether the astronomers and instrument makers of Mosul were still active in 1290 when the Genoese arrived we don’t know, though we may suppose that lower Mesopotamia and the banks of the Tigris now presented a bleak prospect, and Baghdad itself had not yet recovered from the aftermath of the Mongols’ invasion.
The siege of Baghdad in1258 had been followed by decimation of the city’s population, the Mongols’ murder of its ruling classes and their near-obliteration of its intellectual heritage. al-Tusi himself worked in Baghdad under the Mongols, hoping to salvage some of it and notably to save the observatory at Maragha. It was he who revised Ptolemy’s Tables at that observatory.
A contemporary (whom Harris quotes but does not name) said that so many books had been thrown into the Tigris by the Mongol invaders that “they formed a bridge which could support a man on horseback”  and a proverb arose that is repeated to this day: that for six months the Tigris ran black with the ink of books and red with the blood of scholars and the wise.
One community had Hulugai’s protection, for his wife Dokuz Khatun was a Nestorian Christian who asked that her co-religionists be spared. Hulugai is said to have ordered a cathedral built for the Nestorian Catholicos, Mar Makikha.
Baghdad’s once extraordinary collection of ancient Greek texts had begun to be amassed from before the time the Islamic city was built in the eighth century. A philhellene Caliph, al-Mansur (754 AD – 775 AD) began the work of collection and of translation, and it was also he who had the ‘circular city’ built to an auspicious design with advice from astronomer-astrologers from Harran – to that time the capital of the Abbasid caliphate – and assisted too by a formerly Zoroastrian family from Ahvaz near Gundeshapur.
al-Mansur was fortunate that knowledge of paper-making had recently come to the Islamic world; first at Samarkand and then at Baghdad where Chinese prisoners taught the technique, which was then very rapidly and widely introduced.  In my opinion, paper-making plants are depicted on f.2r of Beineke MS 408 
A number of researchers, including the present writer, have raised the possibility that what we now see on vellum in Beinecke MS 408 might have been copied from sources written on paper. Among the reasons for this suggestion are lack of ruling out (paper’s laid lines were used to keep lines of script more or less straight), and the Voynich manuscript’s fairly unusual dimensions.
In any case, the Greek texts had not been translated directly into Arabic. An initial stage – as Dimitri Gutas has emphasised – saw them first translated into Syriac and/or Persian, Arabic translations being made from those. Gutas also notes the paucity of evidence for any translations having been made from Greek into Syriac during the pre-Islamic period, but this may be due to a continuing use of Greek as a lingua franca until Byzantine rule was supplanted by Islamic. The Byzantines themselves were intensely proud of their pre-Christian heritage and their education system retained study of Homer and other classics in the higher school curriculum as long as the Byzantine empire survived.
In early Baghdad, gathering and translating the “wisdom of the Greeks” required no access to Byzantium, for Greek learning had infused the eastern Mediterranean and passed to as far as India. During the rule of al-Ma’mun (caliph in 813) the work begun by al-Mansur accelerated, as demand increased for theoretical and applied scientific knowledge. As if to underline the fact that the acquisition of learning was essential to the growth of Islam, and in keeping with the Prophet’s injunction that in seeking wisdom one should go even as far as China, al-Ma’mun’s administration gave physicians and ‘astrologers’ (i.e. including astronomers and mathematicians) the same rank as that of secretaries of state. 
In medicine, in classical literature and pharmaceutical knowledge, Nestorians were then universally accepted masters at that time, and the former ‘star-worshippers’ of Harran, now called Sabeans, were acknowledged throughout the east at that time as masters of mathematics and astronomy. al-Ma’mun’s granting these professions a rank equal to that of secretaries of state showed respect for learning as a good and served as a public assertion of its importance to Islamic society. Naturally, a far higher rank was accorded scholars of Islamic jurisprudence.
Subsequent generations built on that initial legacy, and although Baghdad’s first glory as the fabulously wealthy seat of the Abbasid caliphate was already fading by the tenth century, Baghdad still held one of the largest collections of classical and Hellenistic Greek works in the medieval world, second to that in Constantinople, perhaps, until 1204, and thereafter surpassed by none – until the libraries were devastated by the Mongols in 1258.
The question of whether any books were printed is a contentious one. Bulliet argues that printing may have been practiced in Egypt by the tenth century and continued there to as late as the Mongol period but no evidence links its use to Baghdad. As it happens, Genoa also saw the brief emergence of printing during the late fourteenth century (1384-6), but that is usually supposed due to influence from north Africa or Spain.
The point of this for Voynich studies is that the means certainly existed as early as the thirteenth century, for older Greek works to have been brought into the west in languages other than Arabic and even in the war-ravaged Baghdad of the 1290s, the same is true. In a sense, it was a parallel situation which brought the Voynich manuscript to public view, and saw it taken first to England and then to America: that is, that in the aftermath of war and despoilation, the desperation of an impoverished community saw remnants of ruined libraries and private collections offered to persons from an entirely different region and native language. This is a constantly-recurring pattern in history, and we have evidence from as late as the nineteenth century which is relevant to our present theme.
A British administrator in Sri Lanka, early in the nineteenth century, was able to gather a large number of manuscripts on the subject of medicine and the majority, as he was informed by their current owners, had come from Baghdad as a gift of the Caliph or had been purchased in Baghdad by one of their own ancestors. 
An active policy of dissemination had seen earlier Baghdad noted for its bookstalls and book-sellers as well as for its public and private collections. Charlemagne also benefited from the Caliph’s generosity. That copies of Greek classical works passed to the Great Sea is beyond doubt. Thus what we see in the Voynich imagery but here particularly in the botanical folios – a basis in Hellenistic custom and thought together with evidence of Asian style in art, and what I take as a final layer appropriate to a mid-twelfth century date and Arabian-Mesopotamian locus – is not at all incompatible with the history of classical texts’ dissemination.
While I do not not think there can be much point in trying to identify any one person as “bearer” – no more than in attempting to identify a single “author” – it is important to show that a text might acquire just that pattern of “layering” during the centuries between the time of the Greeks and the time Beinecke MS 408. I would also note that Theophrastus’ work on plants was constantly mistaken for Aristotle’s, in both the east and the west.
I won’t try to argue that Genoese brought matter in Beinecke MS 408 to Latin Europe – I do not believe. myself, that they did – but it is true that the nature of the content, concerned as it is with valuable products gained from the east and practical matters of maintenance and navigation – would have co-incided with Genoese interests and the reason for their oft-mentioned presence in the east before 1400. In fact the ‘900’ Genoese are said to have died to the last man in Mesopotamia, so we can’t blame them!
Beyond the devastation in Baghdad, however, any others who reached the sea had to pass the ancient site of Teredon/Dioditis. Exactly where it lay is now uncertain.  Rawlinson thought it may have been the site of Ubulla and if that were so, it had served as the place of embarkation for India and the far east for millennium and a half, and indeed in the tenth century al-Mas’ūdi (c. 896–956) spoke of al-Ubulla in connection with the Radhanites, saying too that
“in earlier days, the ships of China used to come.. to al-Ubulla and the coast of Basra.”
At the height of Baghdad’s glory, then, books were plentiful, works of the older Greeks were being translated into various languages and scripts, and disseminated from Baghdad to as far as mainland Europe or north Africa to the west and initially at least as far as India to the east, and a direct link by sea joined the Persian Gulf to south east Asia and perhaps to southern China, yet at that time the only persons recorded as traversing the full extent of that route are said to have been the Radhanites.
In the mid-ninth century, again, we find that al-Ulbulla is mentioned, and again in speaking of the Rhadanites, whose languages included Greek. The Persian master of roads and posts, Ibn Khurradādhbih (820 – 912 AD) describes says of the Mesopotamian route that “they come overland to al-Jabiya on the Euphrates… sail down the Euphrates to Baghdad, then down the Tigris to al-Ubulla, from where they sail the Arabian Gulf to Oman, Sindh, India and China.”
The century after the disastrous journey of the 900 Genoese – all of whom are said to have died in a factional dispute – saw Genoa establish a short-lived factory at Dioskurias (their despatches naming it in the Byzantine style, ‘Sebastopolis’). It would prove another unfortunate venture, and lead directly to the expulsion of all Genoese from the Black Sea – to the benefit of their Venetian rivals.