Shangguan Wan’er, it was said, wore her hair in a lopsided bob, in order to cover up the scar on her face from where Empress Wu went for her with a fruit knife. It was an argument over a boy, of course – the drunken Wu had been fondling a sleeping gigolo and bragging about how he made her heart melt, and Wan’er had foolishly reached out a hand to touch him. So, at least, reads the Secret Record of the Director of the Guiding the Immortal Cranes Bureau, a racy work of historical fiction purporting to have been written in the 900s, but more likely to date from a millennium later. It’s just one of the lascivious works cited in Rebecca Doran’s Transgressive Typologies: Constructions of Gender and Power in Early Tang China, the kind of book that makes you wonder why everyone isn’t studying Chinese history.

Doran is interested in what she calls “the historical period of female power”, from the time that the charismatic Wu Zhao was called back from a Buddhist nunnery as a new distraction for the Gaozong Emperor. She rose swiftly to power behind the throne, first as his empress, then as his interpreter following an unspecified illness likely to have been a debilitating stroke. She ruled behind the throne for the remainder of Gaozong’s life and the truncated reigns of two of their sons, before seizing power herself in the 690s. But Doran, like many other Tang historians, extends the period of female rule beyond the life of Wu, noting that an entire generation of women grew up during her reign, and came to regard equality, or more, as their birthright.

Shangguan Wan’er, Wu’s minister and speech writer, once regarded as the greatest poet of her generation, remained a power-broker after Wu’s death, and latched on to Wu’s grand-daughter Anle as a possible second empress regnant. Anle was brought down in a palace coup by Wu’s daughter and grandson, but the daughter, Princess Taiping, clung on to her own power base for several more years before her ally betrayed her. Depending on how you define it, the “historical period of female power” either spanned Wu’s adulthood and aftermath, c.650-713, or just the last two decades of that period – her years as empress regnant, and the “second generation” of the women who tried to emulate her. After 713, Wu would be vilified for twelve hundred years. It was only in the 20th century, and even then initially for shady political reasons, that Wu began to be reclaimed as a feminist icon, and her period in power regarded as anything but a woeful mistake.

Doran takes as her starting point the Biographies of Exemplary Women from the Han dynasty, because for centuries this book served as the template for good female behaviour. It was a touchstone for all the (male) historians who wrote about Wu and her imitators, and formed the basis of their disapproval. She also examines the life of Empress Dugu of the Northern Zhou, who controversially insisted on monogamy from her imperial husband – regarded by medieval protocol wonks as a “fatal mistake” sure to undermine palace harmony and dynastic vigour. In doing so, she points to the glorious chaos of the century before the Tang dynasty, when a series of tin-pot and occasionally barbaric dynasties contended to become the new Sons of Heaven, with a set of intrigues sufficient to make Game of Thrones look like Emmerdale.

Doran moves on to the reigns of Wu’s sons Zhongzong and Ruizong, and the kind of poetry and imagery that was popular in a world where their mother really ran the show. As Wu began manipulating the news of her era – Fortean phenomena, observations and media, all pointing to a coming paradigm shift – she pushed an agenda rooted in incredibly modern terms. As she argued at the epochal feng-shan sacrifice in her husband’s day, if the world was truly a constant cycle of yin and yang, dark and light, female and male, then women deserved an equal shot at public life, at power, and ceremonial roles. This, in the eyes of her chroniclers, was her dreadful sin, daring to push an equality agenda in a patriarchal world. Doran uncovers delightfully obsequious comments from fawning poets and courtiers, keen to praise Wu and her imitators for simply showing up, for their grace and their wondrous cultural achievements. She also delves deep into the surviving works of Shanggaun Wan’er, and their place in the history of Chinese poetry.

Then things get weird, as Doran examines the Comprehensive Record of Affairs Within the Court and Without, a Tang dynasty fantasy in which a minister is sent to hell over a bureaucratic mistake, witnesses the future of the Ruizong Emperor, and is then restored to the human world in time to live through it all, like some medieval Chinese variant on Back to the Future. She also reports on a common Fortean phenomenon in Wu’s era – transsexual chickens, regarded by Wu’s cronies as examples of her greatness, and by her detractors as symbols of the awfulness of the age. In once farcical scene, a courtier recalls the presentation of a three-legged fowl to Wu, who insists it is an auspicious event worthy of note in the dynastic chronicles, even as her son Ruizong points out that one of the legs is clearly fake. Wu tells him to shut up, but even as she does, the leg falls off.

There’s something quite wonderful about Wu and her courtiers bickering about auspicious bullshit, and Doran’s ongoing citations of gossip and innuendo from the time, such as the nursery rhymes and pop songs that slyly alluded to palace putsches and scandals, and the stories written when later writers tried to grapple with the sheer oddness of her reign. Needless to say, much of the disapproval directed at Wu and her imitators would be framed in familiar, materialist terms, lampooning them for flighty, grasping, gold-digging consumption. Doran begins with a famous poem about Anle putting on her make-up as the soldiers bash down the door to her chambers, observing that there are similarities in the story with the “painted” Jezebel of the Bible. There’s plenty of fun to be had with what today would be called tabloid sniping at Anle and Taiping’s pimped-up chariots, ridiculously opulent palace cribs, and bling-bling fineries.

Doran finishes with a prolonged discussion of the “gender anarchy” of Wu’s era, as described by both apologists and attackers, a sort of topsy-turvy Saturnalia of sexually predatory women and ineffectual men, the elevation of bad-boys and charlatans, and (worst/best of all), the Office of the Crane, Wu’s 120-strong personal harem of pretty boys. One of whom, of course, was the cause of that fateful catfight between Wu and Wan’er. When he was inevitably butchered in the coup that ousted Wu in 705, Wan’er tenderly carried off his penis and presented it to the grieving Empress. That’s what it says in the Secret Record of the Director of the Guiding the Immortal Cranes Bureau, anyway.

Jonathan Clements is the author of Wu: The Chinese Empress Who Schemed, Seduced and Murdered Her Way to Become a Living God.