By Dhani Irwanto, 29 September 2015

Sundaland is a bio-geographical region of Southeastern Asia which encompasses the Sunda shelf, the part of the Asian continental shelf that was exposed during the last ice age. The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 12,000 years ago. It included the Malay Peninsula on the Asian mainland, as well as the large islands of Kalimantan, Java, and Sumatera and their surrounding islands. The eastern boundary of Sundaland is the Wallace Line, identified by Alfred Russel Wallace as the eastern boundary of the range of Asia’s land mammal fauna, and thus the boundary of the Indomalaya and Australasia ecozones. The islands east of the Wallace line are known as Wallacea, and are considered part of Australasia. It is worth noting that it is now generally accepted that South East Asia was probably the entry point of modern humans from Africa. 

Figure 1 – Sundaland map

The South China Sea and adjoining landmasses had been investigated by scientists such as Molengraaff and Umbgrove, who had postulated ancient, now submerged drainage systems. These were mapped by Tjia in 1980 and described in greater detail by Emmel and Curray in 1982 complete with river deltas, floodplains and back swamps. The ecology of the exposed Sunda Shelf has been investigated by analyzing cores drilled into the ocean bed. The pollens found in the cores have revealed a complex ecosystem that changed over time. The flooding of Sundaland separated species that had once shared the same environment such as the river threadfin (Polydactylus macrophthalmus, Bleeker 1858) that had once thrived in a river system now called “North Sunda River” or “Molengraaff River”. The fish is now found in the Kapuas River on the island of Kalimantan, and in the Musi and Batanghari rivers in Sumatera.

The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 12,000 years BP. Scientists consider this Ice Age to be merely the latest glaciation event in a much larger ice age, one that dates back over two million years and has seen multiple glaciations.

During this period, there were several changes between glacier advance and retreat. The maximum extent of glaciation within this last glacial period was approximately 22,000 years BP. While the general pattern of global cooling and glacier advance was similar, local differences in the development of glacier advance and retreat makes it difficult to compare the details from continent to continent.

From the point of view of human archaeology, it falls in the Paleolithic and Mesolithic periods. When the glaciation event started, Homo sapiens were confined to Africa and used tools comparable to those used by Neanderthals in Europe and the Levant and by Homo erectus in Asia. Near the end of the event, Homo sapiens spread into Europe, Asia, and Australia. The retreat of the glaciers allowed groups of Asians to migrate to the Americas and populate them.

Figure 2 – Post-Glacial sea level

The Younger Dryas stadial, also referred to as the Big Freeze, was a geologically brief (1,300 ± 70 years) period of cold climatic conditions and drought which occurred between approximately 12,800 and 11,500 years BP. The Younger Dryas stadial is thought to have been caused by the collapse of the North American ice sheets, although rival theories have been proposed. It followed the Bølling-Allerød interstadial (warm period) at the end of the Pleistocene and preceded the preboreal of the early Holocene. It is named after an indicator genus, the alpine-tundra wildflower Dryas Octopetala.

The Dryas stadials were cold periods which interrupted the warming trend since the Last Glacial Maximum 20,000 years BP. The Older Dryas occurred approximately 1,000 years before the Younger Dryas and lasted about 3000 years. The Oldest Dryas is dated between approximately 18,000 and 15,000 BP.

Bathymetry and Topography

Figure 3 – A map showing the Sundaland around the Last Glacial period (21,000 years BP) generated by the author from the GTOPO30 elevation grids published by USGS. The sea water level was around 120 meter below the present-day sea water level. The flow pattern of the rivers below the present-day sea water level is generated using the same grids and approximations of sea sedimentation, littoral drift, delta formation, meandering, river regime change and river bed movement. The present-day inland rivers are combined. The colors other than blue represent the ground levels. The thin red lines are the present-day shorelines.

Present-day topographic and bathymetric data covering the Sunda Shelf in geographic projection (latitude and longitude) are extracted from the GTOPO30 elevation grids published by USGS. GTOPO30 refers to 30-arc second (approximately 0.9 km near equator) horizontal latitude and longitude spatial resolution of digital elevation model (DEM) file format. Other similar grids like GEBCO_8 published by IHO and IOC/UNESCO, and ETOPO1 published by NOAA are also used as references. A color scheme is applied to the DEM in which areas below -120 m are represented by blue colors so that the Last Glacial Maximum coastlines can be easily identified.

Several assumptions are made in the analytical procedures (Sathiamurthy et al, 2006). First, it is assumed that the current topography and bathymetry of the region approximate the physiography that existed during the span of time from 21,000 years BP to present. However, because sedimentation and scouring processes have affected the bathymetry of the Sunda Shelf over the last 21,000 years (Schimanski and Stattegger, 2005), we know that this is only an approximation. Thus, it should be emphasized that the depth and geometry of the Sunda Shelf and the existing present-day submerged depressions do not reflect past conditions precisely.

Second, it is assumed that the present-day sea bed are likely to have existed during the Last Glacial Maximum and have not resulted from seabed scouring by currents, limestone solution, or tectonic movement-possibilities that were pointed out by Umbgrove (1949) as perhaps taking place during early post-Pleistocene transgression. In the case of tectonic movement, Geyh et al (1979) mentioned that the Sumatera Strait was tectonically stable at least during the Holocene. Furthermore, Tjia et al (1983), state that the Sunda Shelf has been largely tectonically stable since the beginning of the Tertiary. Nevertheless, Tjia et al (1983) indicated that sea level rise in this region may be attributed to a combination of actual sea level rise and vertical crust movement. Hill (1968) in reference to earlier work done by Umbgrove (1949), suggested the possibility of limestone solution as a mode of depression formation (as in the case of the Lumut pit off the coast of Perak, Malaysia), and gave an alternative explanation, which was of tectonic origin.

Sea bed sedimentation data are rarely available but approximation of sedimentation process is made in generating the topographic and bathymetric regional map of Sundaland. In similar conditions, other processes like littoral drift, delta formation, meandering, river regime change and river bed movement are also approximated and incorporated on the maps. Ancient lakes are reconstructed from the DEM and any geological history that exist. Small and insignificant islands are removed.
Along with the topographic and bathymetric map, shorelines at certain sea water levels, ground surface slope, river watersheds and flow pattern of rivers are also generated and place them in different layers.

Figure 4 – A map showing the Sundaland major watersheds around the Last Glacial Maximum period (21,000 years BP) generated by the author using the same method as in the previous figures. River names are given referring to the sea, strait, gulf, island or present day river names occupied by the watersheds.

Present Conditions

Figure 5 – Main active faults in Sundaland at the zone of convergence of the plates of Sunda, Eurasia, Philippines, India and Australia. Smaller plates of Timor and Banda Sea (part of Sunda), Maluku (part of Philippines) and Andaman (part of Eurasia) are also shown. Large arrows represent absolute motions of plates. Red triangles are the volcanoes.

Figure 6 – Plots of major earthquake occurrences ever recorded and their intensities in Mw scales. Note that Sundaland is encircled by earthquake prone lines. (Source: USGS)

Figure 7 – Plots of tsunami sources ever recorded and their created water heights. Note that tsunamis occurred frequently in Banda Sea and Sulawesi Sea that could affect the inner islands. (Source: NOAA)

Figure 8 – Plots of volcano eruptions ever known and their Volcanic Explosivity Indices (VEI). Note for large scale Tambora eruption in 1815 and frequent Krakatau eruptions being the largest in 1883. (Source: NOAA)

Human Migrations

A study from Leeds University and published in Molecular Biology and Evolution in 2008, examining mitochondrial DNA lineages, suggested that humans had been occupying the islands of Southeast Asia for a longer period than previously believed. Population dispersals seem to have occurred at the same time as sea levels rose, which may have resulted in migrations from the Philippine Islands to as far north as Taiwan within the last 10,000 years. The population migrations were most likely to have been driven by climate change – the effects of the drowning of an ancient continent. Rising sea levels in three massive pulses may have caused flooding and the submerging of the Sunda continent, creating the Java and South China Seas and the thousands of islands that make up Indonesia and the Philippines today. The changing sea levels would have caused these humans to move away from their coastal homes and culture, and farther inland throughout Southeast Asia. This forced migration would have caused these humans to adapt to the new forest and mountainous environments, developing farms and domestication, and becoming the predecessors to future human populations in these regions.

Oppenheimer locates the origin of the Austronesians in Sundaland and its upper regions. Genetic research reported in 2008 indicates that the islands which are the remnants of Sundaland were likely populated as early as 50,000 years ago, contrary to a previous hypothesis (Bellwood and Dizon, 2005) that they were populated as late as 10,000 years ago from Taiwan.

The 2009 research and study by the HUGO Pan-Asian SNP Consortium, conducted within and between the different populations in the Asia continent, showed that genetic ancestry was highly correlated with ethnic and linguistic groups. There was a clear increase in genetic diversity from northern to southern latitudes. The study also suggested that there was one major inflow of human migration into Asia arising from Southeast Asia, rather than multiple inflows from both southern and northern routes as proposed before. This indicates that Southeast Asia was the major geographic source of East Asian and North Asian populations. East Asians have mainly originated from South East Asian populations with minor contributions from Central-South Asian groups. The Taiwan aborigines are derived from Austronesian populations. This stands in contrast to the suggestion that this island served as the ancestral “homeland” for Austronesian speaking populations throughout the Indo-Pacific.

Figure 9 – Colored arrows depict the increasing genetic diversification of humans after they migrated eastward along what is now India’s coast and split into numerous genetically distinct groups that moved across Southeast Asia and migrated north into East Asia (Source: HUGO Pan-Asian SNP Consortium)

Riverine Civilizations

Rivers supplied a continuous if not always dependable flow and supply of water for transportation, farming and human consumption. These rivers along with climate, vegetation, geography, and topography shaped the development of the early riverine civilizations. However, while people of these civilizations were dependent on the rivers, the rivers also inspired new technological, economic, institutional, and organizational innovations and developments. Riverine cultures were the cradle of maritime civilizations.

Figure 10 – Riverine civilizations in Sundaland

Sundaland Theories of Atlantis

Some authors have specifically claimed a clear link between Sundaland and Plato’s Atlantis. The Sunda Sub-Oceanic Plain is large enough to match Plato’s description of Atlantis. Its topography, climate, flora and fauna together with aspects of local mythologies, all permit a convincing case to be made to support this idea.

CW Leadbeater (1854-1934) who was a prominent theosophist was perhaps the first to suggest a link between Atlantis and Indonesia in his book, The Occult History of Java. Other investigators have written on the prehistory of the region of whom the best known is probably Stephen Oppenheimer who firmly locates the Garden of Eden in this region, although he makes little reference to Atlantis. More recently, Robert Schoch, in collaboration with Robert Aquinas McNally, wrote a book in which they suggest that pyramid building may have had its origins in a civilisation that flourished on parts of Sundaland that are now submerged.

The first book to specifically identify Sundaland with Atlantis was written by Zia Abbas. However, prior to its publication the Internet offered at least two sites that discussed in detail the case for Atlantis in Southeast Asia. William Lauritzen and the late Professor Arysio Nunes dos Santos developed extensive websites. Lauritzen has also written an e-book that is available from his site, while Santos developed his views on an Asian Atlantis in another recent book, Atlantis: The lost continent finally found. Dr Sunil Prasannan has an interesting essay on Graham Hancock’s website. A more esoteric site also offers support for the Sundaland theory.

April 2015 saw further support for an Indonesian Atlantis with the publication of a book, Atlantis: The lost city is in Java Sea by a hydrologist, Dhani Irwanto, who endeavors to identify features of the lost city with details in Plato’s account with a site in the Java Sea off the coast of the island of Kalimantan.

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Copyright © Dhani Irwanto, 2015. All rights reserved.