But not only is this fortress the key to Turkish Armenia; it also defends the most important of her trade routes. The principal avenue of the commerce between Europe and northern Persia passes through Erzerum. This traffic, which is conducted by means of numerous strings of camels, was originally founded by the Genoese. Its flourishing condition long after the disappearance of these great merchants is attested by the Jesuit missionaries in the latter half of the seventeenth century. [179] As early as the year 1690 we hear of a British commercial agent residing in the city. [180] In those days even a portion of the trade with India found its way through Erzerum. After the initiation of a service of steamers on the Black Sea in the year 1836, the land routes between the provincial capital and Constantinople or the Mediterranean ports gradually fell into disuse. On the other hand, the trade itself received a great impulse, and has continued to increase year by year to the present day. In place of the almost endless stages of land carriage through Asia Minor, European steamers discharge their goods at the port of Trebizond, whence they are conveyed on the backs of camels through Erzerum and along a series of plains to the Persian city of Tabriz. In the year 1842 it was ascertained that the number of packages disembarked at Trebizond in transit for Persia was about 32,000. In 1898 this trade had increased to over 5000 tons; and in a normal year the value of the imports into Persia is about £600,000. About two-thirds of this trade belongs to Great Britain. It is to be hoped that the trunk railway which already exists in Asia Minor will be extended to Erzerum, where it should be joined by a branch line from Rizeh or Trebizond. From Erzerum it could be continued without the intervention of any natural obstacle through Bayazid to Tabriz; and from Tabriz it would proceed through Teheran and Ispahan until it effected a junction with the Indian railways. The capital to construct this railway should be subscribed in Europe generally; and a certain percentage of interest should be guaranteed on the revenues of Turkish Armenia as a provincial unit, as well as on the revenues of Persia.