When did the country of Bhutan disappear from the map?

The poster should be talking about the country Sikkim, not the Kingdom of Bhutan. It is a small place between Nepal to the east and Bhutan to the west, and it is close to Shannan, Tibet Autonomous Region of my country. Yadong County is one of the 15 countries bordering the People's Republic of China and China. Historically, Sikkim was once a territory of China and a territory of Tibet for more than 1,200 years from the 7th century to 1890. Sikkim is now occupied by India. In ancient Chinese books, ancient Sikkim was named Zhe Mengxiong. The Nepalese who immigrated here called it the "new place", and the early Tibetan immigrants called it Dengjiang, which means the Valley of Rice. As far back as the 7th century AD, Zhe Mengxiong was part of Tubo (Tibet). In the 9th century, Zhemengxiong became an independent tribe, but the monasteries within its territory were still affiliated with major monasteries in Tibet. The "Peace Treaty between India and Sikkim" was signed in December 1950, stipulating that Sikkim is a "protectorate" of India, and India controls Sikkim's defense, diplomacy, economy and other powers. In August 1968, anti-India demonstrations broke out in Gangtok, demanding the abolition of the "Peace Treaty between India and Sikkim". In April 1973, India implemented military occupation of Sikkim. On June 20, 1974, the Sikkim Parliament adopted the Sikkim Constitution drafted by India, which stipulated that the chief administrative officer sent by the Indian government was the head of government and the speaker of the parliament. In September of the same year, the "Amendment to the Indian Constitution" stipulated that Sikkim is an "associated state" of India, with one seat for Sikkim in each of the two houses of India. Sikkim has now been completely annexed by India. Except for the Thirteenth King of the Namugal Dynasty, who is still in exile in New York to seek for his kingdom to regain its independence, most of the people of Sikkim—or most of the people living in Sikkim—have long identified with India. sovereignty over Sikkim. In 1975, the Indian army disbanded the King of Sikkim's palace guard and placed the King of Sikkim under house arrest. On April 10 of the same year, the Sikkim Assembly passed a resolution to depose the king and turn Sikkim into a state of India. On April 14, Sikkim held a "referendum" to determine the future of Sikkim. Afterwards, the Indian Parliament passed a resolution to officially turn Sikkim into a state of India. On January 29, 1982, King Palden Dundup Namgar of Sikkim passed away in New York, USA. Crown Prince Wangchuk Tensing Namgar ascended the throne and became the 13th King of Sikkim. He announced that India would invade Sikkim. The annexation is illegal. After the annexation of Sikkim, the Indian government is afraid that Sikkim will become independent again, so it allocates a subsidy to Sikkim every year to attract Sikkim's centripetal force. Therefore, generally speaking, Sikkim is richer than its neighboring Bangladesh, and the people's living standards are also higher. Then, the Kingdom of Sikkim ceased to exist on the map. It is now the Indian State of Sikkim, and the number of countries bordering China has increased from 15 to 14. I hope you will be satisfied with the reply.