[Footnote 35: See Holland, Studies, pp. 40-58; Walker, History, I. pp. 204-212.]
(2) There were, secondly, collections of Maritime Law of great importance which made their appearance in connection with international trade. From the eighth century the world trade, which had totally disappeared in consequence of the downfall of the Roman Empire and the destruction of the old civilisation during the period of the Migration of the Peoples, began slowly to develop again. The sea trade specially flourished and fostered the growth of rules and customs of Maritime Law, which were collected into codes and gained some kind of international recognition. The more important of these collections are the following: The _Consolato del Mare_, a private collection made at Barcelona in Spain in the middle of the fourteenth century; the _Laws of Oléron_, a collection, made in the twelfth century, of decisions given by the maritime court of Oléron in France; the _Rhodian Laws_, a very old collection of maritime laws which probably was put together between the sixth and the eighth centuries;[36] the _Tabula Amalfitana_, the maritime laws of the town of Amalfi in Italy, which date at latest from the tenth century; the _Leges Wisbuenses_, a collection of maritime laws of Wisby on the island of Gothland, in Sweden, dating from the fourteenth century.
[Footnote 36: See Ashburner, "The Rhodian Sea Law" (1909), Introduction, p. cxii.]
The growth of international trade caused also the rise of the controversy regarding the freedom of the high seas (see below, § 248), which indirectly influenced the growth of an International Law (see below, §§ 248-250).
(3) A third factor was the numerous leagues of trading towns for the protection of their trade and trading citizens. The most celebrated of these leagues is the Hanseatic, formed in the thirteenth century. These leagues stipulated for arbitration on controversies between their member towns. They acquired trading privileges in foreign States. They even waged war, when necessary, for the protection of their interests.
(4) A fourth factor was the growing custom on the part of the States of sending and receiving permanent legations. In the Middle Ages the Pope alone had a permanent legation at the court of the Frankish kings. Later, the Italian Republics, as Venice and Florence for instance, were the first States to send out ambassadors, who took up their residence for several years in the capitals of the States to which they were sent. At last, from the end of the fifteenth century, it became a universal custom for the kings of the different States to keep permanent legations at one another's capital. The consequence was that an uninterrupted opportunity was given for discussing and deliberating common international interests. And since the position of ambassadors in foreign countries had to be taken into consideration, international rules concerning inviolability and exterritoriality of foreign envoys gradually grew up.