In Peninsular Malaysia a mountainous spine known as the Main Range or Banjaran Titiwangsa runs from the Thai border southwards to Negeri Sembilan, effectively separating the eastern part of the Peninsula from the western. A considerable part of the interior of Kelantan, Terengganu and Pahang is also mountainous and contains the highest peak in the Peninsula, Gunung Tahan (2187 m). As a result of the configuration of the country and of the heavy rainfall, there are many rivers which, until just over one hundred years ago, formed the main arteries for trade and travel and whose historical importance is underlined by the fact that nearly all of the states of the Peninsula take their names from the principal river in each. The longest of these rivers is the Sungai Pahang (475 km), followed by the Sungai Perak (400 km).
The rivers of Sarawak and Sabah are longer than those of the Peninsula. The longest is the Rajang of Sarawak (563 km) which is navigable for small coastal steamers as far as Kapit, 160 km upstream. One of the most prominent mountain ranges in Sabah is the Crocker Range with an average of 457 to 914 m, which separates the narrow lowland of the north-west coast from the interior. The Crocker Range culminates in Gunung Kinabalu (4101 m), the highest mountain in Malaysia and in Southeast Asia. Malaysia’s third highest mountain, Gunung Tambuyukon (2579 m) is close by, while the country’s second highest peak, Gunung Trus Madi (2597 m) is in the same range. In Sarawak the two highest peaks are Gunung Murud (2425 m) and Gunung Mulu (2371 m) which also boasts one of the largest natural caves in the world.
About four-fifths of Malaysia are covered by tropical rain forest. Rice cultivation is practised throughout the Peninsula but the main and traditional centres are the states of Perlis, Kedah and mainland Pulau Pinang. Newer areas for large-scale rice cultivation are also to be found in Perak, Selangor and Kelantan. Most of the larger rubber and oil palm estates are located on the West Coast of the Peninsula, as are also the nation’s main tin deposits.
Malaysia lies entirely in the equatorial zone. The climate is governed by the regime of the north-east and south-west monsoons which blow alternately during the course of the year and whose existence in the days of sailing ships made the country the natural meeting and exchange point for traders from East and West. The north-east monsoon blows from approximately mid November till March, and the south-west monsoon between May and September, the periods of change between the two monsoons being marked by heavy rainfall. The period of the south-west monsoon is a drier period for the whole country, particularly for the other states of the west coast of the Peninsula, sheltered by the land mass of Sumatra. Being in the tropics the average temperature throughout the year is constantly high (26o C). The diurnal
temperature range is about 7o C. Regional variation in temperature and rainfall is mainly due to relief, e.g. Cameron Highlands has a mean temperature of 18% C and an annual rainfall of over 2500 mm compared to Kuala Lumpur’s 27o C and 24lO mm. Near the coasts, land and sea breezes modify the temperature, while being surrounded on virtually all sides by sea results in the Peninsula’s rather equable climate. Mornings are generally fine and convectional rainfalls in the late afternoons are often accompanied by lightning and thunder. The humidity is high (about 80%) due to the high temperature and a high rate of evaporation, and the rainfall is heavy (more than 2500 mm)