The catalogue of Armenian manuscripts at the French National Library tells an interesting story of how the pre-revolution holdings were assembled.
It all starts when Francis I of France entered into a treaty with the Grand Turk, and established a permanent ambassador in Constantinople. This opened the Turkish state to French scholars in search of Greek texts. Bindings of Henri II in the Royal collection show that Armenian manuscripts were being acquired in the middle of the 16th century. But it was only in the second half of the 17th century, under the influence of Colbert, that a definite policy of acquiring Armenian mss came into being, as an official letter to the traveller Antoine Galland (1646-1715) shows, sent just before his third voyage to the East in 1679. This instructed him to buy:
“…all the ancient Armenian books that can be found, and above all books of history by a certain author named Moses [of Khorene] in that language; also Armenian translations of the bible, written in ancient times, because an Armenian bible has recently been printed in Holland.” 
Colbert was interested in Armenian affairs, not least because there was an Armenian colony at Marseilles involved in the trade to Persia and India, and he arranged for Louis XIV to grant permission on 11 August 1669 to an Armenian bishop-cum-printer Oskan of Yerevan to operate at Marseilles. This in turn sparked interest among Paris litterateurs like Richard Simon and Eusebe Renaudot in what bishop Oskan was doing. These court Catholics made use of creeds as part of the literary war against Protestantism, to demonstrate the antiquity of catholic formulations. A Dominican sent by Colbert to Ethiopia acquired one Armenian ms. in Cyprus on the way. Others were bought from French merchants or travellers. In this sort of way 165 Armenian mss were gathered in the Royal library alone prior to the French Revolution.
Colbert himself acquired mss, as did other great persons of state or religious orders. The collection of Renaudot went with the rest of his rich library to the Maurist fathers of St. Germains-des-Pres, which was seized at the revolution.
The first French scholar to interest himself in the study of the Armenian language was Petis de la Croix (1653-1716). His father had been secretary-interpreter to the French ambassador in Constantinople for more than 20 years, from 1670. De la Croix himself was a translator for the king. He left a large Armenian-French dictionary in manuscript, assisted probably by the former Armenian patriarch of Constantinople and Jerusalem, who had been removed from Constantinople by the ambassador, the Marquis de Feriol, and held under arrest in the Bastile from 1706 until his death in 1711. During his arrest the patriarch copied a number of Armenian mss now in the BNF. Renaudot was authorised to negotiate with him concerning his possible release and return to the East.
A mission to the East in 1728-30 by Sevin and Fourmount resulted in the acquisition of 134 pieces. A letter home by Sevin on 22 Dec. 1728 reveals optimism:
“Most of the works of Nestorius, Dioscorus, and some other famous heretics, have been translated into that language [Armenian] and it would be important to recover them, as well as various historical pieces composed in ancient times by the Armenians. One of them, a friend of Fonseca, flatters himself that he has the power to supply us with these things but as the books of the Armenians are very carefully written and also mostly decorated with figures of plants and animals, a very high price is placed on them, which prevented me from buying the six that he brought to me, consisting of New Testaments, Rituals, and translations of St. Chrysostom, which it would be easy to find again.”
In a last minute note on the same letter Sevin adds:
“Since I wrote the above, Mr. Fonseca has shown us in a house 160 Armenian mss, i.e. more than there are in all the libraries of Europe altogether, and even in all of Constantinople. These mss are composed of commentaries on scripture, translations of the fathers, ancient works of theology and books of history; the most important is that of Armenia, which is not to be had at Paris for less than £500. We have been promised also the history of the martyrs of Palestine by Eusebius, a piece which we don’t have in Greek, and which would throw a considerable light on the first three centuries of the church. The acquisition of so many manuscripts in one language is very important, and there would be some risk in awaiting your order to buy it.”
Sevin went on to buy the mss anyway, for a total of £15,000, an incredible sum, and then, naturally ran into difficulties. Sevin also stated that he would have to steal one ms, because the church to which it belonged could not sell its possessions. The end result of his efforts, tho, was to substantially augment the holdings of the library further.
 Henri Omont, Missions archeologiques francaises en Orient au XVIIe et XVIIIe siecles, 1, Paris, 1902, p.206.