On this world the Toba Catastrophe took place in 70,114 BC. This event created an evolutionary bottleneck in numerous species as their numbers dwindled during the six years of winter that followed. In the aftermath of this event on this timeline homo sapiens would quickly share the Earth with a second fully sapient species, the Lophrotus, a divergent species from Orangutan in the aftermath of the Toba eruption.
The city of Gohk'Ra was founded on a large island that would eventually take the same name (Borneo in the OTL). It was the center of the first civilization created by the Lophrotus. The founding of Gohk'Ra is used as the basis of the calendars of the Lophtus people, while the exact date is lost to the mists of history the calendar starts on the equivalent of 4002 BC in the original time-line.
In circa 2200 GC the Swarnabhumi Empire was formed. Human incursions into Lophrotus lands aided the various island tribes in uniting. The empire would reach its height in about 2700 GC, even controlling some of the jungles of Southeast Asia. Their chief rival during this later time was the Kingdom of Mahajanapada in south Asia. A strong rival to humanity aided in the growth of a stronger central authority on the sub-continent of India.
Given geography of their homelands and their own biology the Lophrotus became the earliest seafaring power on Earth. Control of the seas around their territory kept the Lophrotus safe from major invasion of humanity. They leveraged this power in their own expansion into the jungles on the continent. The rivalry between these two sapient species would continue for thousands of years.
While called the Swarnabhumi Empire this political entity was more of a confederation of city-states by a pro-trade central authority. While economics was not as developed as it would be many centuries later, attempts were made by the authority to facilitate trade and mediate disputes between the Lophrotus tribes. The main purpose of the Empire would be to create a navy and army to hold back human expansion. By 2700 GC, after five centuries of growth, it truly became an empire. The citizenry was left relatively alone except for levies and taxes, but a powerful military existed in its northern and western reaches.
The military is bronze-age. Spears, bows, bolas, and swords are the most common weapons. A typical Lophrotus soldier wears less armor than their human counterpart. They prefer to keep the weight of equipment down and like to keep a wide range of motion available since they still climb trees. They are even developing their own martial arts to exploit their own racial advantages and exploit human weaknesses.
Tin, copper, and gold are natural resources of the early empire. While humans first invented bronze the Lophrotus quickly copied it and have abundant supplies. Early farming techniques were poor with the foods available but as sea travel became more common fishing became a major industry. With the stable food supply from fishing the Lophrotus population began to grow.
The lumber and oil resources are being adapted for ship building. Many other resources of the region will become more valuable in future centuries as technology progresses. Many communities also have thriving bone carving and primitive textile production.
On an individual level the economy is still a bronze-age barter system. Trade between cities or other sections of the 'Empire' use gold and sometimes copper.
As with human religions there is a wide range of deities for various concepts, cities, professions, etc. The most popular deities are those which embody trees or the sea. Their god of evil and tyranny, Zareerin, has a very humanlike appearance.
Sixty-thousand years is probably a long way off of the time needed for orangutans to evolve into the Lophrotus. But I didn't want to create a random divergence point set millions of years ago. I wanted to set a specific date to the Toba Catastrophe and play around with both human and orangutan history.
Maybe I'm just looking forward to this year's Dawn of the Planet of the Apes. Just classify this one as ASB.
The name lophrotus, which the species named itself, I took from a synonym for orangutan from 1813, Lophotus - which I then discovered is now used for a genus of crestfish. I took the name, added an R and that was that.
The name of the empire, Swarnabhumi, was taken for a name of Sumatra in Sanskrit ("Land of Gold"). Some cross-contamination linguistically between species or random chance lead to the name in the timeline.