The primary reason that south and east Asia are combined into a single region is the shared history of the nations that comprise it. As of 2014, 11 countries make up the region of Southeast Asia.
The region of Southeast Asia started to develop around the 17th century, when European imperialism dominated the area. The opening of trade routes drew Europeans to the area. The Portuguese arrived first, followed shortly by Great Britain. The countries in the area were rich in exotic spices and textiles that drew a lot of money from Europeans, who were beginning to use the expensive imports to highlight their wealth. The British Empire established Singapore specifically as trading post to compete with the primarily Dutch-occupied Indonesia. For the next few centuries, European nations fought for control of the nations that now comprise Southeast Asia. The occupation of the region by European nations spurred massed immigration into the region. In the years after World War II, many of the colonies of Southeast Asia began to declare independence from the European nations that ruled them. The economy of Southeast Asia continued to prosper, however. As of 2014, it is reported to be the fastest growing economy in the world.