The districts of the island conform in a great measure to its natural divisions. However, political reasons have modified the natural boundaries and increased the districts to six by division. These districts are Parang, Pansul, Lati, Gi'tung, Lu'uk and Tandu. The first district on the west is Parang. A line joining the western limit of Bwalu on the south coast, with a point slightly east of the summit of Mount Tumantangis, and projected to the sea on the north, delimits this district on the east and carves out of the western natural division the district of Pansul. The eastern boundary of Pansul is a line running from a point 2 or 3 miles east of Maymbung to Mount Pula and Busbus. The chief reason for separating Pansul from Parang was to reserve for the sultan direct control over Jolo and Maymbung. This district has more foreigners residing in it than any other. A line joining Su' and Lubuk marks the eastern limit of both Lati and Gi'tung, the third and fourth districts. The watershed line joining the summits of Mounts Dahu, Tambang, and Sinuma'an and falling on the east to the vicinity of Su', divides Lati on the north from Gi'tung on the south. For all practical purposes the district of Lati may be said to lie between Jolo and Su', and the district of Gi'tung or Talipao between Maymbung and Tu'tu'. The land joining Si'it and Tu'tu' is low. Sulu traditions say that when the Samals arrived in the island this neck of land was submerged and the island was divided by a channel of water. The extinct volcano of Pandakan, generally spoken of as the "Crater Lake," which lies in this vicinity, may be of late origin and may have been the source of the geologic deposits which helped to fill the channel. Spanish records speak of a volcanic eruption in the vicinity of Jolo as late as 1840, and it is very likely that other volcanic action occurred prior to that date and after the arrival of the Samals in the fourteenth century. A line joining Limawa on the north and Sukuban or Tandu Panu'an on the south, divides Lu'uk from Tandu, thus forming the fifth and sixth districts respectively. A line joining Mount Tayungan and Bud Tandu divides both Lu'uk and Tandu into a northern and a southern part. In both cases the southern parts are more fertile and better cultivated and probably more thickly populated than the northern.