It was the promise of gold that first brought the traders of my people to these lands. It was said that it was as common as the sand on the beaches and that even the people of the lowliest cast possessed golden artefacts to adorn their fingers, necks and ears. While that was an exaggeration, gold is still valued and prized amongst the wealthy and powerful, it is certainly more abundant here than anywhere else.
The people of Sundaland are in want of tin, since the earth here does not yield much of it. Luckily that is something we can supply and the trade in one for the other is thus mutually beneficial. There are some tin mines in the central areas of this land but access and control of them are often contested and even the cause of wars.
You might ask, why is tin deemed worthy of a trade for gold and something to shed blood for? Well it is necessary for the creation of bronze with which to fashion both the strongest plow and the sharpest spear.
- An Account of Sundaland by Alom Takal
Knowing how various natural resources are distributed in an area can give insight into how local economies developed and can provide a background for geo-political tensions. Just think about the importance of oil and other natural resources for what has happened over the past 100 years. In previous times it was much the same, however metals were what was sought after.
Access to better metals meant you could create better tools and weapons. It's not my intention to work out a detailed resource economy but to provide inspiration and ideas for why for example a certain city is located somewhere or why one city state wishes to attack the other. These are great hooks for stories and adventures.
Ancient people were aware of seven different metals:
https://en.wikipedia.org/wiki/Metals_of_antiquity
Gold:
https://en.wikipedia.org/wiki/Gold
Silver:
https://en.wikipedia.org/wiki/Silver
Copper:
https://en.wikipedia.org/wiki/Copper
Tin:
https://en.wikipedia.org/wiki/Cassiterite
Lead:
https://en.wikipedia.org/wiki/Lead
Iron:
https://en.wikipedia.org/wiki/Iron
Mercury:
https://en.wikipedia.org/wiki/Mercury
I imagine this setting as having a Bronze Age level of technology. While iron was known by ancient people it has a much higher melting point than the other metals and requires a more complicated procedure to forge and work with. Iron objects are very rare and usually produced by more advanced societies. Meteoric iron was also used, but again it requires advanced technology to forge.
Gold and silver are found natively meaning that once mined they are immediately ready to use. The others have to be processed first. Gold is relatively abundant in the area and stimulated traded with India and China in later times. Panning was a common according to this in depth article:
Gold in early South East Asia. As far as I know Bronze Age societies didn't use currency but relied on trading goods or were run as so called Palace Economies (the central authority collected and redistributed resources as needed) but perhaps a relative abundance of gold could allow for the invention and use of currency.
Edit: Recently I've read research that indicates currencies were indeed used in the Bronze Age although not always in the form of coins.
Bronze was very important since it allowed the creation of stronger tools and weapons. Bronze is an alloy consisting of roughy 88% copper and 12% tin. In fact some Bronze Age societies of the Eastern Mediterranean would trade batches of copper and tin ingots in a ratio of 9 to 1.
Copper is roughly 20 times as common as tin so the latter was the more valuable resource. The ancient Egyptians, Hittites etc. relied on tin from Afghanistan and some scholars liken it to oil in terms of its scarcity and importance to their civilisations.
Wikipedia: Tin sources and trade in ancient times
In the map below I've labelled areas where metal ores are found using various public resources (I've included the highly valuable Jade as well as Obsidian). I've taken liberty to add in two extra sources of copper to ensure enough abundance for a Bronze Age similar to what occurred in the Eastern Mediterranean from roughly 3300 to 1200 BC. These are located in what is now South Vietnam and West Borneo.
The main tin deposits are in what is now Malaysia and central Sundaland (click to enlarge). Whomever has control of sources of tin controls who can create bronze in the entire subcontinent. There are tin deposits in what is now Burma and Northern Thailand but they won't be easily accessible as those areas are highlands and covered in dense forests, it might be that they haven't even yet been discovered. Perhaps, as told in stories of Alom Takal, there was trade of tin from what is now Afghanistan, through India and across the Bay of Bengal?
Remember that this map only shows a fraction of the river systems and that most of the landscape is covered in various types of forests and jungles. Natural resources might be abundant but that doesn't mean they are easy to access.
