A weeping young emperor is escorted to his palanquin by a stern-faced warlord, on the grounds that there are “bandits everywhere.” The warlord in question has already burned another prince alive, and the “bandits” are his own, sinister men.

For two hundred years from the fourth to the sixth century AD, northern China was over-run by a group of nomads. Much like many others in Chinese history, they leeched off the locals, established themselves as the new aristocracy, and soon began to squabble about whether to hang onto their “barbarian” ways or go completely native. By the end of their reign, they had moved in to the former capital of the Eastern Han dynasty, filling it with newfangled Buddhist temples and statuary. Their “Northern Wei” dynasty, in only ruling part of China, is one of those that are often edged out of histories, despite its idiosyncratic and original works of art and culture, and its larger-than-life rulers, who stick out in Chinese museums like an alien invasion.

Dzyip-yip-ken, for example, the “crimson lord” stands six feet six inches, with hair that trails on the ground. He’s by no means the weirdest character in Scott Pearce’s delightful new book, The Northern Wei: A New Form of Empire in East Asia.

A nomad ruler claims to be the son of a maiden who descended from heaven in a glowing chariot. Discredited nobles live in fear of being assigned to the Wuhuan, a “vanguard suicide unit” that defends the border. A war band gains a new leader when they sacrifice a horse to a dragon, and the fearsome beast transforms into a young boy.

Pearce is gleefully aware that his diligently referenced and entirely accurate account of the dynasty that ruled north China from 386 to 534 AD reads more like a fantasy novel, noting on one occasion that he is describing “a tableau that seems scripted for a B-movie.”

“The brutality,” Pearce writes, “the barbarism of this age is almost unspeakable.” A minister “solves” a refugee crisis by drowning 8,000 people. A court lady smuggles an infant crown prince out of a harem massacre by shoving him down her trousers. An emperor is driven mad by the Daoist potions he is drinking as an aphrodisiac. Another manages the remarkable feat of siring over a dozen sons on a dozen women before dying, presumably of exhaustion, at just 23. A fallen minister is taken to his place of execution in a caged carriage, and before he dies, is urinated on by an entire company of guardsmen.

The world Pearce describes is joyously alien, where people have names like Bjij, Xae-ljen and Jijlej of the Bulwukku. They called themselves the Taghbach, although the term, like all the others, was elided and sanitised by Chinese historians, turning them into the Tuoba. Spears trail “toad streamers”, and prospective empresses must demonstrate their ability to forge a golden statue. Baffled Chinese chroniclers attempt to make sense of spats, vendettas and blow-ups between the aristocracy, which often lapse into Taghbach slang, while the Taghbach themselves prey upon the people of northern China like a coterie of elegant vampires. The Northern Wei was a regime that turned China upside down, often scandalously privileging the role of women in its society. It was, notably, the era that gave us The Ballad of Mulan, and which began to establish the rise to prominence of women as leaders and political actors. Two centuries later, its legacy would turn into the backlash against the “transgressive typologies” of an era of women in power.

At the start of the era, the Taghbach are dismissive of Chinese ways. One scoffs: “Try putting on Han silks and then riding around on your horses through the brush and brambles.” But as the regime wears on, the “braidhead caitiffs” (as they were called by their southern enemies) are slowly assimilated into Chinese ways. They are lured into Chinese customs, take Chinese wives, and eventually, with their original capital at Datong creaking at the seams and unsustainably large, relocate off the steppes to Luoyang, the former capital of China.

On the way, they pack local culture with new and unusual differences, some of which would endure ever after. As attested to by their magnificent statues and carvings at Luoyang and Datong, they fervently embraced the foreign religion of Buddhism, (founding, for example, the Shaolin Monastery) jamming it so deep into Chinese culture that it never left. Pearce notes many other influences, including the increasing presence of women in social and political life. He points out that imagery of Han dynasty banqueting shows womenfolk peeking in from a balcony while the men enjoy themselves. By the Dark Ages, the ladies were dining in their own separate chamber. But it’s under the Northern Wei that women come to control the feast – overseeing the menu and the food, and even leading the diners in song.

As for the Northern Wei, it fizzles out in a cataclysm of bed-hoppings and stabbings, as the shadowy families behind the scenes fight to put one of their own on the throne in a time of climate crisis, interpreted by soothsayers as heavenly displeasure, manifesting in droughts, diseases and crop failures. Marital politics dominates the court, in a “complexity that is perhaps wearisome for the modern reader” writes Pearce, who is entirely sorry-not-sorry about a history book that ends with an Empress Dowager proclaiming that her hostile teenage son’s newborn daughter is really a boy, and therefore the new emperor… before grudgingly changing her mind.

It actually gets even crazier after that. For Pearce, this amounts to a book-length prologue to his 1987 Princeton doctoral thesis, The Yü-wen Regime in Sixth Century China – which outlines the even more bonkers rise and fall of the short-lived successor dynasty, the Northern Zhou, but that is another story…

“The city had been destroyed before,” he writes of the glorious Luoyang, “and would of course be destroyed again.”

Jonathan Clements is the author of A Brief History of China. The Northern Wei: A New Form of Empire in East Asia is published by Oxford University Press.