The Natuna, the Anamba, and the Tambilan islands, which stretch across the entrance of the China sea between Borneo and the Malay peninsula, were common lurking haunts of the pirates. Amongst these islands they could find water and shelter; could careen, clean, and repair their prahus; and they were right in the track of vessels bound to Singapore, or northward to the Philippines or China. To replenish their stores and to obtain arms and ammunition they would sail to Singapore in innocent-looking captured prahus, where they found a ready market for their booty amongst the Chinese. Muskets of English make and powder from English factories were found in captured prahus and strongholds. At Patusan a number of barrels of fine gunpowder from Dartford were discovered exactly as these had left the factory in England. Against these the Rajah was powerless to take the offensive. They had to be left to be reduced or cowed by the spasmodic efforts of British men-of-war. What he urged, though ineffectually, was that a man-of-war should patrol the coast and curb the ruffians. What was actually done, but not until later, was to attack and burn a stronghold or two, and then retire. The pirates fled into the jungle, but returned when the British were gone, rebuilt their houses, and supplied themselves with fresh vessels. Near at hand were the Saribas and Sekrang Sea-Dayaks occupying the basins of rivers of these names, the Sekrang being an affluent of the Batang Lupar. In each of these rivers was a large Malay community of some 1000 fighting men who lived by piracy, and who trained the numerous Dayaks, by whom they were surrounded, to the same lawless life that they led themselves, and guided them on their predatory excursions. Here again both Dayaks and Malays were under the influence of Sherips, Mular, his brother Sahap, and others. In course of time these Dayaks became expert seamen, and, accompanied by the Malays, yearly issued forth with fleets composed of a hundred or more bangkongs,[112] sweeping the seas and carrying desolation along the shores of Borneo over a distance of 800 miles. The Sea-Dayaks soon became aware of their power; and accordingly, both in their internal government and on their piratical expeditions, their chiefs attained an authority superior to that of the Malay chiefs, their titular rulers.