In 1722, China's Kangxi emperor - sixth ruler of the Manchu-led Qing dynasty - named his son, the soon-to-be Yongzheng emperor, as his heir.

The Qianlong emperor as a young man

The choice was made not because Yongzheng was next in line for the throne, or that he was Kangxi's favourite son. Instead, Yongzheng was chosen for the love of Kangxi's grandson, Hongli.

Of the 10 children the future Yongzheng emperor had produced, Hongli was the Kangxi emperor's favourite. His temperament, mannerisms and interests reminded the emperor of himself.

Showing an aptitude for martial arts and literature, Hongli was favoured for the throne by his father also, but when he became Prince Bao after Yongzheng succeeded the throne, he faced a tense battle with his older half-brother, Hongshi.

Unknown to Hongli, his sibling was plotting against him with the support of many court officials and his uncle Yinsi, Prince Lian. He had been doing so years before either of them would become emperor.

Deterred by their conflict, Yongzheng refused to name a crown prince, but it was clear Hongli would take up his mantle eventually: his father gave him a number of important tasks in preparation for his future rule and he was invited to attend military and political meetings far beyond his position.

Visionary artist, poet and scholar

A magnificent scroll painting of the emperor viewing some of his artworks

Hongli came to the throne in 1735, taking the name Qianlong ("lasting eminence") aged 24. His brother, Hongshi, was stripped of the family name and forced to commit suicide - yet was posthumously reinstated.

The young emperor immediately set about proving himself a worthy heir of Kangxi and Yongzheng. While expanding the territories of the Qing dynasty through military might, he also placed a huge importance on his cultural obligations.

Like his illustrious grandfather, Qianlong realised that the support of China's populace was as vital as military strength for Manchu rulers, who were not native leaders, but a foreign conquering force. He was careful to embrace the arts from each of the cultures he presided over, with the vision of harmony in a multi-ethnic state.

For the first time, China would have a compilation of the Manchu language, genealogy and history. As a Buddhist, he cemented the Qing claim in central Asia by commissioning a replica of Tibet's Potala Palace built in the imperial summer palace.

Not a modest man, the emperor also had a Tibetan thangka painted to show him as Manjusri, the bodhisattva of wisdom.

The imperial collection

The emperor's impressive military costume

However, the Qianlong emperor's most consuming passion was the royal collection: an amassment of the greatest works of art and jewels acquired by China's leaders since the first century BC.

The collection had "gone through many vicissitudes of fire, civil wars and foreign invasions in the centuries that followed", according to Gerald Holzworth in his book, China: the Three Emperors. The Qianlong emperor poured hours of dedication into restoring and adding to the collection, acquiring China's greatest private collections to return his to its former glory.  

One of the first great art collectors, Qianlong "carefully followed the art market in rare paintings and antiquities, using a team of cultural advisers, from elderly Chinese literati to newly fledged Manchu connoisseurs," adds Holzworth.

The artworks were Qianlong's prized possessions, and he took his entire collection on trips across China just to compare them with the real landscapes. The scroll paintings adorned the walls of every palace that he visited.

He regularly added his inscriptions and short poems to the paintings in his collection, following the example of his predecessors. Of course, this makes the pieces more valuable to collectors today, but the idea of a modern buyer putting their mark all over a work of contemporary art doesn't bear thinking about.

Some of these inscriptions, added to only the most beautiful or meaningful paintings, served as something of a diary for the emperor, as he recorded his musings on their creation. On one work of art he wrote the following poem, which suggests he was a deep-thinking sort:

"One or two
My two faces never come together yet are never separate
one can be Confucian, one can be Mohist
why should I worry or even think?"

Treasures at court

The Qianlong's emperor's jade seals were used to give his approval on official documents and were often created to mark special occasions

Jade, the most coveted gem in China, was of particular interest to the Qianlong emperor. Many of the jade pieces in the imperial collection were added during his reign, with the massive seals he used to give approval to official documents or mark certain occasions among the finest examples of his jade obsession.

Sotheby's recently sold one such seal, created to mark his 70th birthday. The "Seal of the 70 year old Son of Heaven" made $1.5m at 2013's Asia Week New York. Learn more about the Qianlong seals here.

Yet, the emperor's nurturing of China's myriad cultures did not just encompass the nation's treasure, but also extended to the West. Hundreds of Western scholars and specialists flocked to the court, either employed by the emperor or sent on official duties.

One Englishman, sent by George III to arrange trade deals, wrote:

"The Emperor is about five feet ten inches in height, and of a slender but elegant form; his complexion is comparatively fair, though his eyes are dark; his nose is rather aquiline, and the whole of his countenance presents a perfect regularity of feature, which, by no means, announce the great age he is said to have attained; his person is attracting, and his deportment accompanies by an affability, which, without lessening the dignity of the prince, evinces the amiable character of the man.

"His dress consisted of a loose robe of yellow silk, a cap of black velvet with a red ball on the top, and adorned with a peacock's feather, which is the peculiar distinction of mandarins of the first class. He wore silk boots embroidered with gold, and a sash of blue girded his waist."

The emperor seems a rather attractive character, and his preservation of China's cultural treasure was certainly honourable. Yet, there was a darker side to his collecting obsession…

A dangerous obsession

The Siku Quanshu - an invaluable record or a thinly disguised method of suppression?

In acquiring China's greatest private collections, the Qianlong emperor is known to have done all in his power to possess them. His power being absolute, no doubt the owners were given little compensation for the loss of their items and wealth.

Marring his illustrious name further is the notorious Siku Quanshu project, for which a team of China's finest scholars was assembled to produce the largest collection of Chinese philosophy, history and literature ever seen.

A noble pursuit, yet the emperor used Siku Quanshu, or Four Treasuries project, to wipe the writings of his political and historical enemies from the face of the planet.

The Siku Quanshu was published in 36,000 volumes, and in the 10 years of its creation, 150,000 irreplaceable texts were burnt or banned.

In addition, there were 53 cases of "literary inquisition" (or speech crime) during the emperor's reign. Punishments ranged from beheading or mutilation to "slow slicing" - a torture method reserved for the worst of crimes, in which the victim is tied to a pole and then has body parts sliced off until death.

Yet such barbarism was commonplace in the judicial systems of many of the world'