Maritime Southeast Asia is the maritime region of Southeast Asia as opposed to mainland Southeast Asia and comprises what is now Malaysia, Brunei, Philippines, Singapore, Indonesia, and Timor Leste. The local Malayo-Polynesian name for the region is Nusantara. Maritime Southeast Asia is sometimes also referred to as "island Southeast Asia" or "insular Southeast Asia". The 16th-century term East Indies, and the later 19th-century term Malay Archipelago refers to a largely similar area.
This main demographic difference that sets Maritime Southeast Asia apart from Indochina is that its population predominantly belongs to the Austronesian (Malayo-Polynesian, Melanesian and Micronesian) groups, although through trade with neighbouring groups from the Asian mainland like the Tai-Kadai, Austroasiatic, or Chinese, as well as other Oceanic groups like Papuans and Negritos there has been significant intermixing and cultural exchange.
The prevailing cultures of this region are maritime-based, tribal, and predominantly non-sinicized (except for Singapore, and, to a significant albeit lesser extent, Malaysia). Kingdoms based on Java and Sumatra such as Srivijaya and Majapahit spread similar cultural motifs throughout the subregion's five countries (gong ensembles such as gamelan and kulintang are one example). Maritime Southeast Asia makes up the oldest bloc within Austronesia, with the Philippine archipelago representing the urheimat of all Malayo-Polynesians (non-Formosan Austronesians).
Over 540 million people live in the region[when?], with the most populated island being Java. The people living there are predominantly from Austronesian subgroupings and correspondingly speak western Malayo-Polynesian languages. This region of Southeast Asia shares social and cultural ties with the peoples of mainland Southeast Asia and with other Austronesian peoples in the Pacific. Islam is the predominant religion, with Christianity being the dominant religion in the Philippines and Timor Leste. Buddhism, Hinduism, and traditional Animism are also practiced among large populations.
Historically, the region has been referred to as part of Greater India, as seen in Coedes' Indianized States of Southeast Asia, which refers to it as "Island Southeast Asia"; and within Austronesia or Oceania, due to shared ethnolinguistic and historical origins of the latter groups (Micronesian and Polynesian groups) being from this region.
Historians have emphasized the maritime connectivity of the Southeast Asian region whereby it can be analyzed as a single cultural and economic unit, as has been done with the Mediterranean basin. This region stretches from the Yangtze delta in China down to the Malay Peninsula, including the South China Sea, Gulf of Thailand and Java Sea. It is argued that many of the peoples connected in this trade network had more in common with one another than their inland neighbors, thus the utility of analyzing it as a single cultural and economic unit. However, this maritime Southeast Asian region differed from the Mediterranean in that, historically, there was a single dominant political and economic power driving trade and exchange, China.
Historian Anthony Reid argues that this Southeast Asian region entered an 'age of commerce' between the early 1400's and the 1600's. This age of commerce sparked the multicultural and transnational dynamics which forged the region into a single maritime unit. Demand for Southeast Asian products and trade was partially driven by the increase in China's population in this era, whereby it doubled from 75 to 150 million. The naval expeditions of Zheng He between 1405 and 1431 also played a critical role in opening up the Southeast Asian region to increased trade.
China's role in Southeast Asian maritime trade can also be seen in the growing Hokkien diaspora which emigrated to various cities in the region throughout this period. Despite not having the official sanction of the Chinese government these communities formed business and trade networks between cities such as Melaka, H?i An and Ayutthaya.
Sino-Southeast Asian trade had been going on since at least the 9th century, but their prominence in Southeast Asian port cities greatly expanded in this era. Many of these Chinese businesspeople integrated into their new countries, becoming political officials and diplomats.