But there is more to divinity than a title, as known by Jayavarman VII. A string of royal assassinations and years of occupation of the Khmer capital by the Cham had thoroughly destabilised the Khmer Empire. At this time the Jayavarman VII, then a general and already in his 50s, comes into historical prominence. He led a critical naval battle against the Cham (again, we see the Khmer's almost divine connection with with the waters of their land) and ousted them from the capital, then went on to unite squabbling political factions and was crowned king.
A general seizes the throne after years of instability - in any other story, this is where you might expect the zealous grabbing of power and aggressive expansion to happen. But Jayavarman was not an young man with dreams of glorious sea-spanning empire. He was a devoted Mahayana Buddhist, and his declared aim was an end to suffering. He identified himself strongly with Lokeśvara, known to the wider Buddhist world as Avalokiteśvara, the Bodhisattva of Compassion.
It is important to clarify that Buddhism is not the worship of a deity in the classical sense. The Buddha was born a man like any other, who found enlightenment under the Bodhi tree. To be Buddhist is to worship human potential as divine, rather than a divine 'other'. Enter the Bodhisattva, figures who are capable of escaping the cycle of Samsara, but commit the ultimate compassionate act - they forgo their own personal Nirvana to stay here with us, trapped in Samsara, to help us attain Enlightenment. So to be specifically known as the 'Bodhisattva of Compassion' in a field that already requires the ultimate compassionate sacrifice just as cost of entry - you've got to be a really nice guy.
So Jayavarman VII modelling himself as Lokeśvara was a proclamation with some theological weight. And as we've established, Buddhism is all about walking-the-walk. A ritual and a crown can make you Devaraja, but it cannot make you Lokeśvara, the living embodiment of compassion. So off Jayavarman VII set to put an end to suffering. We've already touched on his Ārogyaśālā (his network of 102 public hospitals) but he was also responsible for countless Dharmasala - 'fire houses' - shelters for pilgrims travelling the Khmer lands. His reign ushered in highways, reservoirs, temples (including notably grand ones like the Bayon) and other previously unheard of levels of public infrastructure - as Wikipedia puts it, "a welfare state that served the physical and spiritual needs of the Khmer people".
He lived until 95(!), giving him time to put such grand plans in motion. While his reign was a period of stability for the Khmer, it was not one that outlasted him. With his death began a long decline for the Khmer Empire. We don't know exactly what dealt the 'killing blow' to Khmer power in the region due to a lack of 15th century sources (there was certainly some kind of 'incident' sparked by ballooning Siamese influence), but we know their grand hydraulic megacities like Angkor Wat and Angkor Thom were abandoned by the Khmer people (who you might know today as 'Cambodians') in favour of a new capitals like Longvek and Phnom Penh. As we move into a more climate-aware world, scholars increasingly shift their lens towards the relationship between the Khmer people and their environment. The elaborate hydraulic infrastructure of Angkor Wat is as impressive as it is fragile. Tree rings reveal evidence of drought conditions during the period - could the waters that lifted the Khmer Empire so high have been their downfall?

The political model of the Mandala state is a way scholars interpret decentralised authority in medieval Southeast Asia. Powerful political centers radiated influence outward, like a Mandala pattern, rather than states aligning to rigid borders, claims and territories. It has also been envisioned as a 'solar polity' - imagine the grand city of Angkor Wat as a sun, with other federations and tributary states orbiting its gravity like little planets. And Angkor Wat had quite the gravity pull - before the Industrial Revolution, it was the largest city in human history, occupying an area larger than modern Paris.
This tradition lets the player model such a grand metropolis with a massive growth boost that's doubled during your Golden Ages. With this tradition and the wider emphasis on food, attaining the maximum population in your capital is very possible for the dedicated player. Wait, 'maximum population?' - what you might not know is that triggering a growth event when you have no workable tiles left will spawn a migrant. Choose not to move the capital on age transition (or simply grow it big enough it doesn't matter) to ensure a steady stream of migrants through this tradition, primed to colonize spice islands as Majapahit or fill the forests of Dai Viet.