The Rajang, Kinabatangan and Pahang: The Waterways That Shaped Malaysia

Before the Pan Borneo Highway or MASwings flights existed, the only way to reach the interior of Sarawak was to travel upriver for days on end. Today’s major towns — Sibu, Kapit, Sandakan, Pekan — did not come to exist at their locations by chance. Each one sits where the river decided: at a river mouth, at the confluence of two rivers, or at the furthest point still navigable by ship. Three rivers — the Rajang, the Kinabatangan and the Pahang — show this pattern most clearly.

The Rajang: Sarawak’s main highway

The Rajang River is Malaysia’s longest river. According to the official portal of the Sarawak State Government, it runs 563 km from the Iran Mountains in central Borneo, flowing south-west as far as Kapit before turning west and ending at the South China Sea.

What makes the Rajang significant is not just its length, but how far it can be navigated. The same portal records that sea-going ships can sail 130 km upstream as far as Sibu, while small boats and sampans can continue a further 160 km into the interior that is otherwise difficult to reach by land. It is this limit of navigation that explains why Sibu — not Kuching — grew into the trading centre for the whole of central interior Sarawak.

Sibu also holds a chapter of migration rarely associated with this river. In 1900-1901, a Christian scholar from Fujian, China, Wong Nai Siong (Huang Naishang), travelled along the Rajang in search of new settlement land for his people. Following an agreement with the Brooke administration in Kuching, three groups of migrants — numbering more than 1,100 people in total — arrived at the Sungai Merah area near Sibu between late 1900 and mid-1901, clearing land for pepper, rubber and other crops. The nickname “New Foochow” that has stuck to Sibu to this day originates from that event.

The Kinabatangan: the river that sustains Borneo’s richest swamp forest

In Sabah, the Kinabatangan River plays a similar role but with a different outcome. The official website of the Sabah State Government records its length as 560 km, flowing from the Crocker Range to the Sulu Sea east of Sandakan — making it the longest river in the state.

Unlike the Rajang, which shaped a trade route, the Kinabatangan’s significance rests more on the floodplain it forms in its lower reaches. This area has become one of the densest concentrations of wildlife anywhere in Borneo — home to the Bornean orangutan, the proboscis monkey, the Bornean elephant and numerous hornbill species. Much of this lower floodplain has been gazetted as a wildlife sanctuary under Sabah state law, and it is now a focus of ecotourism that supports local communities along the river.

The Pahang: the Peninsula’s artery connecting coast and interior

The Pahang River, meanwhile, is the longest river in Peninsular Malaysia — a status confirmed by the official portal of the Pahang State Government as one of the state’s principal geographic features. Formed at the confluence of Sungai Jelai and Sungai Tembeling near Kuala Tembeling, it flows through towns such as Jerantut, Temerloh and Maran before reaching Pekan, Pahang’s royal town at the river mouth, and onward to the South China Sea.

The same pattern repeats here: Pahang’s major towns are arranged along the river’s course, not by distance from the coast. Before federal highways connected the east coast to the Klang Valley, the Pahang River and its tributaries were the main route carrying forest produce, rubber and trade goods from the interior to the port at Pekan.

Common mistakes

“The Rajang River is 770 km long.” This figure is widely repeated across various secondary sources, but the official portal of the Sarawak State Government itself states 563 km as the full distance from the Iran Mountains to the South China Sea. Discrepancies like this commonly arise when different sources measure different tributaries or use inconsistent measurement methods.

“Malaysia’s longest river must be the most economically important.” Length and economic importance are not necessarily closely related — the Kinabatangan, shorter than the Rajang, contributes major value through ecotourism and wildlife conservation rather than through transport or trade.

What’s next

To understand why these rivers sit where they do — and how mountain ranges shaped the country’s entire settlement pattern — read How Mountains and Monsoons Shaped Settlement in Malaysia. For broader context on the division of Malaysia’s two landmasses separated by the South China Sea, read Peninsular Malaysia and Borneo. And to understand the rainforest and biodiversity sustained by rivers like the Kinabatangan, read Malaysia’s Climate and Biodiversity.