During the colonial era, the region was contested among European colonial powers, notably British and Dutch. From the 17th to early 19th century, various states, ports and cities in the region were held as Dutch colonies or British possessions. The current borders between Indonesia and Malaysia were basically inherited from those established by the colonial powers through their treaties. The Anglo - Dutch Treaty of 1814 and 1824 significantly shaped the territories of Indonesia, Malaysia, Singapore, and India. These treaties officially divided the archipelago into two: Malaya, which was ruled by the United Kingdom, and the Dutch East Indies, which was ruled by the Netherlands. The successor states of Malaya and the Dutch East Indies are Malaysia and Indonesia, respectively. The line that separated the spheres of influence between the British and the Dutch ultimately became the border between Indonesia and Malaysia.
what caused the malay world to be divided into two countries now known as malaysia and indonesia
The Anglo - Dutch Treaty of 1814 and 1824