East Indies - Students | Britannica Kids | Homework Help

The geographic position of the East Indies astride significant wind systems and trade routes has profoundly influenced its history. Its climate and geologic activity have formed its land and created the archipelago.

Once, geologists believe, there were no islands in the ancient sea that separated Asia and Australia. Earth’s outer layer is divided into many rigid blocks, called tectonic plates, that move slowly over Earth’s surface. Some of the islands of the East Indies were created when an undersea plate began colliding with another plate. The heat and movement of one plate overriding the other raised ridges of crust, and the tops formed islands. These geologic forces are evident today in the geysers, active volcanoes, and frequent earthquakes that occur throughout the East Indies. Other movements of the plates are evident in the twisted form of some islands, such as the four arms of Celebes.

The seas between the islands are very shallow, and currents are strong. It is difficult for large ships to pass between most of the islands, and it is a long way around them. For centuries, ships trading between Europe, Africa, the Arabian Peninsula, and India from the west and China, Japan, and the western United States from the east have passed between Sumatra and the Malay Peninsula through the deep water known as the Strait of Malacca.

The distribution of plants and animals in the East Indies, along with other evidence, has led scientists to conclude that some of the western islands were once connected by land to mainland Southeast Asia. New Guinea was once joined to Australia. The relatively shallow seas between the Malay Peninsula and the islands of Sumatra, Java, Bali, and Borneo are less than 300 feet (90 meters) deep. Animals of the mainland—such as tigers, rhinoceroses, and apes—are found on these islands. On islands to the east, however, the animals are like those of Australia. The naturalist Alfred Russel Wallace mapped this division, now known as Wallace’s Line, and published it in 1869. In studying the way birds were spreading and changing in species among the islands, Wallace arrived at the theory of evolution independently from Charles Darwin.

The lush tropical forests, palms, ferns, bamboos, and brilliant flowers of the East Indies form part of its fable. They result from an equatorial climate that is generally hot and wet. The rainfall in most places is between 100 and 150 inches (250 and 380 centimeters) a year. At sea level the temperature in most places is between 80° and 90° F (26° and 32° C) all year long. The islands are mountainous, however, and many places lie within the rain shadow of a mountain and get little or only seasonal rain. On the higher mountains and plateaus the climate is subtropical, and the peaks above 10,000 feet (3,050 meters) have a cool climate and even snow. The more northerly islands are strongly influenced by the monsoon winds in their rainfall patterns.

The shifting winds were very important for trade and navigation until the steamship was developed in the 19th century. Merchants sailed from China to Sumatra on the northeast monsoon, stored their goods in warehouses, and took on cargo from India or the Middle East. Then on the southwestern monsoon they sailed back to China while merchants arrived from India, unloaded their cargoes, took aboard the Chinese goods in the warehouses, and returned to India with the next northeastern monsoon. In this way cities and empires flourished in the Indies.