Early west-coast trade centres are few in number as they were overshadowed by Kedah. Her nearness to the entrances to the Straits of Malacca — and more importantly — being on latitude 6° north of the equator, the same as Ceylon to the south of India, meant that ships sailing the Bay of Bengal in a sea lane heading due east or west between the two were in little danger of becoming lost. The early transpeninsular routeway is part of the sea trade route of the Spice Route for Arab, Persian, Tamil Nadu and India-to-China traders, as the route through the Straits does not seem to have been in general use. Early sea traders from the west, upon reaching the coast, engaged porters to transport goods by raft, elephant and man-carry along the rivers (Kelantan River, Pattani River, Pahang River, Muda River, Bernam River, Muar River, and others) to the opposite coast. The Sungai Muda in particular favoured the development of Kedah.