The external commerce of the Tagalog tribes was principally with China, of which nation there were vessels in Manila on the arrival of the Spanish. They are also said to have had intercourse with Japan, Borneo, and Siam. They had no coined money, but to facilitate trade they utilized gold as a medium of exchange in the form of dust and ingots, which were valued by weight. Magellan speaks of their system of weights and measures. These people were skilful shipwrights and navigators. The Bisayans were in the habit of making piratical forays among the isles. Their vessels were of various kinds, some being propelled by oars or paddles, and others were provided with masts and sails. Canoes were made of large trees, and were often fitted with keels and decks, while larger vessels, called virey and barangayan, were constructed of planks fastened with wooden bolts. The rowers, with paddles (busey) or oars (gayong), timed their work to the voices of others, who sung words appropriate to the occasion and by which the rowers understood whether to hasten or retard their work. Above the rowers was a platform (bailio) on which the fighting men stood without embarrassing the rowers, and above this again was the carang, or awning. They sometimes used outriggers (balancoire) on both sides of the vessel. The laip and tapaque were vessels of the largest kind, some carrying as many as two hundred and fifty men. The barangayan, a type of vessel used from the earliest times, was singularly like those of the ancients described by Homer.