Write a realistic, plausible alternate history scenario in the form of a history book chapter completely set in the world of the alternate history secenario with absolutely no references to real life, OTL or that this is even an alternate history timeline at all, in which the post-1802, pre-1945 Vietnameized side branch of the post-1368, pre-1662 Ming dynasty's ruling over the eighteen provinces of Han China's reigning imperial family, the Han Chinese Imperial House of Zhu of the Vietnamese Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty ruled absolute imperial dynastic royal monarchy of the Empire of Vietnam ruling over Vietnam, which also had the post-1707, pre-1975 Laotian Khun Lo dynasty-ruled unitary parliamentary absolute royal democratic monarchy of the Kingdom of Laos in Laos and the Cambodian House of Norodom-ruled Unitary parliamentary constitutional elective royal monarchy of the Kingdom of Cambodia in Cambodia as puppet states, satellite states and tributary kingdoms, [the Empire of Vietnam] is [the Empire of Vietnam] more firm in stating its [the Empire of Vietnam's] status as [the Empire of Vietnam's legal and political status] a simultaneous continuation, revival, modernization and reincarnation of the Ming dynasty's rump state of the post-1644, pre-1662 Southern Ming occupying [what the Southern Ming occupied] Southern Han China and Cantonia [Guangdong and Guangxi] which [the Southern Ming] had [what the Southern Ming] had the rump kingdom/satellite state/tributary state of the Ming dynasty based in southwestern Taiwan and the Pengu Islands, the Tungning Kingdom ruled [the Tungning Kingdom] by [the Tungning Kingdom's reigning royal family]  the partially Han Chinese heavily sinciced side branch of the reigning Japanese imperial family, the supposedly Shinto-descended Japanese Imperial House of Great Yamato, the Royal House of Koxinga/Zheng dynasty as [what the Royal House of Koxinga/Zheng dynasty ruled the Tungning Kingdom as] its [the Tungning Kingdom's] reigning royal family [the Royal House of Koxinga/Zheng dynasty] while [the Southern Ming] maintaining legal and nominal control over  Han Chinese-Korean Royal House of Jeonju Yi-ruled impoverished royal absolute dynastic monarchy of the Great Joeson State/Kingdom of Great Joeson/Great Joeson Kingdom/Great Joeson/Joeson ruling [the Great Joeson State] over [the Great Joeson State's territories] the entire Korean peninsula, [the Southern Ming having control over both the Tungning Kingdom in Taiwan and maintaining nominal control over Joeson in Korea] before its [the Southern Ming's] conquest by [who conquered the Southern Ming] the Manchu-ruled and Manchu dominated absolute imperial constitutional parliamentary federal monarchy of the Manchu Imperial House of Aisin-Gioro-ruled Great Qing Empire ruling [the Great Qing Empire] over [the Great Qing Empire's territories] East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan along with Han China from [the Great Qing Empire's stronghold, powerbase and homebase] Greater Manchuria, [the Southern Ming being conquered by the Great Qing Empire] in [when the Southern Ming conquered the Great Qing Empire] in 1644, [the Empire of Vietnam being more firm in stating its status as a modern incarnation, modernization and restoration of the Southern Ming] when it [the Empire of Vietnam] is [the Empire of Vietnam] formed, with the founding leader and first member of the  Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty to reign over the Empire of Vietnam as the Emperor of Vietnam, Nguyễn Phúc Ánh, who [ Phúc Ánh] had [what Phúc Ánh had] the era name of [Phúc Ánh's era name] Gia Long when he [Phúc Ánh] ruled over Vietnam as the Emperor of Vietnam, [Long] openly proclaiming that he [Long] is the next Chinese Emperor after the last member of the Imperial House of Zhu to rule over the Southern Ming as the Emperor of Han China, Zhu Youlang, who [Youlang] had the combined regal and era name of [Youlang's combined era and regal name] Yongli, [Long openly proclaiming himself to be the next Chinese Emperor after Yongli] and [Long] even enforcing the secret religion of the Imperial House of Zhu when it ruled over China as its reigning imperial family though the Ming dynasty, Sunni Islam, [Long enforcing Sunni Islam] as the state religion of the Empire of Vietnam and even restoring Ming-era government and military offices, bureaus along with political and military structures in Vietnam after the formation of the Empire of Vietnam, even though he [Long] still pays tribute to the clan heads of the House of Aisin-Gioro ruling over the entire China region as Emperors and Empresses of the Great Qing Empire respectively and [Long] still makes the Empire of Vietnam into a Qing tributary state like in real life.

Long also provides secret support to the secret society which had helped the Ming seize control of Han China in 1368, before the clan heads of the Imperial House of Zhu ruling over the Ming dynasty as Emperors of Han China suppressed it after the formation of the Ming dynasty,  the syncretic religious and political movement which forecasts the imminent advent of the "King of Light" (明王), i.e., the future Buddha Maitreya, which appealed to many Han Chinese who found solace in the worship of the Queen Mother of the West while being hybrid movement of Buddhism and Manichaeism that emphasised Maitreya teachings and strict vegetarianism; its permission for men and women to interact freely was considered socially shocking, the White Lotus Society, [Long providing secret support to the White Lotus Society] in Han China while [Long] also [what Long also does] interact with the Turkish Imperial House of Osman-ruled Unitary parliamentary constitutional imperial royal Islamic monarchy that was one of the only true successor states to the Roman Empire, the Sublime Ottoman State, that [the Sublime Ottoman State] had its [the Sublime Ottoman State's] homebase in [where the Sublime Ottoman State's homebase and stronghold was] modern day Turkey, [the Sublime Ottoman State] maintaining consistent control over Syria, Palestine, Iraq, the Suez and ruling over what is now Saudi Arabia, Oman, Jordan and Yemen via proxies and [the Sublime Ottoman State] maintaining nominal control over Egypt and Libya, [Long interacting with the Sublime Ottoman State] and [Long] taking instructions and advise on modernization and development from another Islamic power [the Sublime Ottoman State], [Long] using this knowledge to develop, modernize and improve the Empire of Vietnam, which pays off later as the Empire of Vietnam is able to enforce Vietnamese control over Laos and Cambodia, resist French colonization of Indonesia, make the Sultanate of Brunei into a Vietnamese tributary state and seize the island of Hainan from the Qing during the Opium Wars between the Qing and the French and British Empires, while also taking all of Cantonia from the Qing under Long's successors, essentially making the Empire of Vietnam into a modern day version of the post-204 BC, pre-111 BC Han Chinese Zhao dynasty/Triệu dynasty-ruled Nanyue Kingdom ruling over [the Nanyue Kingdom's territories] Guangdong, Guangxi, Hainan, Hong Kong, Macau, southern Fujian and central to northern Vietnam.

When  the 10 October 1911 – 12 February 1912 Xinhai Revolution against the Great Qing Empire lead by  the Han Nationalist, Han supremacist, republican, Chinese nationalist, anti-Qing and Han expansionist secret society/political organization/militant group of the Tongmenghui founded [the Tongmenghui] by [who founded the Tongmenghui] the Cantonese Hakka-medical student turned Han nationalist, revolutionary, politician and statesman Dr. Sun Wen, [Wen] better known as Dr. Sun Yat-Sen, [the Tongmenghui founded by Wen/Yat-Sen] in [where Wen/Yat-Sen founded the Tongmenghui] the supposedly Shinto-pantheon-descended,, Japanese Imperial House of Great Yamato/Minamoto dynasty-ruled unitary parliamentary semi-constitutional royal imperial monarchy of the Great Japanese Empire/Empire of Japan/Great Empire of Japan/Great Japan/Imperial Japan/Third Japanese Empire] ruling [the Great Japanese Empire] over [the territories ruled over by the Great Japanese Empire] Sahlakin and the Kurils, the Korean peninsula, Taiwan and the Pengu Islands, Palau, the Carolinas and the Marinas from [the Great Japanese Empire's homebase] the Japanese Home Islands and Okinawa, [Wen/Yat Sen founding the Tongmenghui in the Great Japanese Empire] in [when Wen/Yat Sen founded the Tongmenghui in the Great Japanese Empire]  20 August 1905 after [what Wen/Yat Sen was doing before, while and after he founded the Tongmenghui in the Great Japanese Empire] studying [Wen/Yat Sen in the Great Japanese Empire] under the Japanese alias Kikori Nakayama [when Wen/Yat-Sen studied in the Japanese Empire under the name Nakayama] from 1899 to 1903, [the Xinhai Revolution lead by the Tongmenghui] and [who else lead the Xinhai Revolution against the Qing] the millennialist Chinese folk religious sect focused on militant self-defense and tax resistance along with romanticised monarchism, wishing to restore the pre-Qing Han Chinese Imperial House of Zhu-ruled absolute imperial dynastic royal monarchy of the Great Ming State/Great Ming Empire/“Ming dynasty” as the government of China, the Yellow Sand Society, [the Xinhai Revolution by the Tongmenghui and the Yellow Sand Society] against the Qing breaks out, the then Emperor of the Empire of Vietnam, Nguyễn Phúc Bửu Lân, [Bửu Lân] having the era name of [Bửu Lân's era name] Thành Thái, [Thành Thái] decides to use this opportunity to reclaim the old lands [the sixteen provinces of Han China excluding Guangdong and Guangxi] the main branch of the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty [the Imperial House of Zhu] once [the Imperial House of Zhu] ruled over [Han China], [Thành Thái deciding to reclaim Han China and restore the Ming dynasty as the government of China from the Empire of Vietnam during the Xinhai Revolution] and [Thành Thái] sends out the main military forces of the Empire of Vietnam, the Quân thứ [Second army |Quân thứ|], [Thành Thái sending out the Quân thứ against the crumbling Qing rule in the China region in order to reclaim Han China and restore the Ming dynasty as the government of China from the Empire of Vietnam during the Xinhai Revolution] which mostly succeeds as the Great Qing Empire's post-1895 modernized army corps, envisioned as a regular and professional fully trained and equipped according to Western standards with a reserve, the New Army, [the New Army] is [the New Army] distracted with [what distracts the New Army during the Xinhai Revolution] putting down the Tongmenghui and Yellow Sand Society, with Thành Thái heading to Han China himself [Thành Thái] during the anti-Qing campaigns during the Xinhai Revolution and [Thành Thái] convincing the Yellow Sand Society that  the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty is [ the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty] in fact the true Chinese royal family [the Imperial House of Zhu] just in exile in Vietnam which it [the Imperial House of Zhu in Vietnam as the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty] uses [Vietnam] as a stronghold [the Empire of Vietnam] and [Thành Thái] personally negotiate with the top dog in the New Army, the Han Chinese Yuan Shikai, [Thành Thái negotiating with Shikai during the final days of the Xinhai Revolution] as  East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan all [ East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan] break away [ East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan] from the Great Qing Empire, along with Han China more specifically the Qing stronghold and homebase of Manchuria during and after the Xinhai Revolution like in real life but [ East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan] all [ East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan] remain independent [ East Turkestan, Tibet, Shaanxi, Inner and Outer Mongolia, Tuva, Guangdong, Guangxi and Yunnan] from both Han China and Manchuria after the Xinhai Revolution into the rest of the 20th century into the 21th century and beyond like in real life, leading to the Xinhai Revolution ending in this timeline with the restoration of the Ming dynasty as the government of Han China through the Empire of Vietnam, or in other words the post-1912, pre-1928 and again post-1937, pre-1945 as a Japanese protectorate stratocratic [military-ruled/military governed] with a bicameral national legislature consisting of a Senate and House of Representatives known as the National Assembly Beiyang Government ruling [the Beiyang Government] over Han China after the Xinhai Revolution, [the Beiyang Government] is [the Beiyang Government] never formed as the presidential parliamentary republic of the first Republic of China in this timeline after the Xinhai Revolution and [the Beiyang Government in this timeline] is [the Beiyang Government in this timeline] always the unitary constitutional parliamentary imperial royal monarchy under a military dictatorship of the Empire of China formed by Yuan Shikai in 1915 in real life, [the Beiyang Government never being formed as the first Republic of China but as the Empire of China in 1912 after the Xinhai Revolution in this timeline], but with Thành Thái as its [the Empire of China's] first Emperor and the descendants of the main branch of the Imperial House of Zhu in China subsequently being absorbed into the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty upon the Empire of China's formation via both monogamous and polygamous marriages, concubinages and adoptions to reunite the main lines of the Chinese imperial family [the Imperial House of Zhu] to form one united reigning Chinese imperial family instead of Yuan Shikai becoming Emperor of Han China in 1915 like in real life. 

Upon the reclaimation of the homeland [Han China] by the descendants of the Chinese imperial family [the Imperial House of Zhu] in Vietnam now ruling over Vietnam as its [Vietnam's] imperial family [the Imperial House of House of Nguyễn Phúc/Nguyễn-dynasty ] after the Xinhai Revolution in this timeline, Thành Thái's young son, Nguyễn Phúc Vĩnh San, [Vĩnh San] becomes [what Vĩnh San becomes after the restoration of the Ming dynasty in Han China through the Empire of Vietnam after the Xinhai Revolution in this timeline] the next Emperor of Vietnam under the era name Duy Tân, but doesn't govern Han China,  establishing a informal "dual-monarchy" for both Vietnam and China akin to that seen in Austria-Hungary.