Ice Age

Definition
Ice age is a time temperature drop during long periods in the earth's climate, causing an increase in the breadth of ice in the polar regions and mountain glaciers. Geologically, the ice age is often used to refer to the time the ice sheet in northern and southern hemisphere; with this denifisi we are still in an ice age. In laymen, and to over 4 million years kebelakangan, the definition of an ice age is used to refer to a colder period with extensive ice cover in the entire continent of North America and Europe.
The cause of the ice age one of which is due to the aerosol cooling process that often befall the planet. The eruption of Krakatoa is one such example on a small scale while one of the dinosaur extinction theory (Chicxulub collision) is one example of a large scale.  
Last Ice Age
In terms of the angle of view of the above, the last ice age began about 20,000 years ago and ended about 10,000 years ago or in the early Holocene time (late Pleistocene). The process of melting ice in this age is relatively old and some experts proved this process ended about 6,000 years ago.  
Ice Age in the archipelago
When the ice age, surface sea water is much lower than now, because a lot of frozen water in polar regions. At that time the South China Sea is dry, so the western archipelago joined with mainland Southeast Asia. Meanwhile, the Papua New Guinea is also affiliated with the Australian continent. After the events of melting ice, the wave of human migration to the archipelago started happening.