When the Scandinavians had firmly established themselves on the Irish coasts they developed trade to a considerable extent, not only by bringing Ireland into communication with their new settlements in England, but also by opening up commerce with Iceland and Scandinavia, and even with Russia and the East.[122] Before A.D. 900 at all events, they had been accustomed to visit France from Ireland, and had trafficked with merchants there, using a certain vessel called the ‘Epscop’[123] for measuring their wine. That this branch of their trade was in a flourishing condition in the latter half of the tenth century may be inferred from a contemporary poem in which Brian Borumha is said to have exacted as tribute one hundred and fifty vats of wine from the Norsemen of Dublin, and a barrel of red wine every day from the Limerick settlers.[124] The Scandinavians also made marked advances on the old methods of trading by building their forts near the large harbours and carrying on from there a continuous overseas commerce.[125] Previous to this foreign merchants[126] who visited Ireland used to exchange their goods for home produce at the numerous _oenachs_ or fairs held at certain intervals all over the country. These _oenachs_ continued to be celebrated during the Viking period, but it was in the seaport towns, Dublin, Limerick, Cork, Wexford, and Waterford, that the most important trade was centred. Dublin, owing to its splendid position, half way between the Continent and the Scandinavian settlements in Scotland and Iceland, and within easy distance of England, became one of the wealthiest towns in the West. One Irish chronicler gives a glowing account of the treasures carried off from there by the Irish after the battle of Gleann Máma (A.D. 1000): “In that one place were found the greatest quantities of gold, silver, bronze, and precious stones: carbuncle-gems, buffalo horns, and beautiful goblets… much also of various vestures of all colours were found there likewise.”[127] Dublin is frequently mentioned in the sagas and seems to have been very well known to Icelandic dealers. In _Olaf Tryggvason’s Saga_ (_Heimskringla_) we read that during the reign of Olaf Cuaran a merchant called Thórir Klakka, who had been on many a Viking expedition, went on a trading voyage to Dublin, “as was usual in those days.”[128] When _Olaf’s_ son, Sihtric Silken Beard, was King of Dublin (c. 994) the Icelandic poet Gunnlaug Ormstungu sailed from England to Ireland with merchants who were bound for Dublin.[129]