Sikkim (/ˈsɪkɪm/) is a state in northeastern India. It borders Tibet in the north and northeast, Bhutan in the east, Nepal in the west, and West Bengal in the south. Sikkim is also located close to India’s Siliguri Corridor near Bangladesh. Sikkim is the least populous and second smallest among the Indian states. A part of the Eastern Himalaya, Sikkim is notable for its biodiversity, including alpine and subtropical climates, as well as being a host to Kangchenjunga, the highest peak in India and third highest on Earth. Sikkim’s capital and largest city is Gangtok. Almost 35% of the state is covered by the Khangchendzonga NThe Kingdom of Sikkim was founded by the Namgyal dynasty in the 17th century. It was ruled by a Buddhist priest-king known as the Chogyal. It became a princely state of British India in 1890. After 1947, Sikkim continued its protectorate status with the Republic of India. It enjoyed the highest literacy rate and per capita income among Himalayan states. In 1973, anti-royalist riots took place in front of the Chogyal’s palace. In 1975, the monarchy was deposed by the people. A referendum in 1975 led to Sikkim joining India as its 22nd state.
Modern Sikkim is a multiethnic and multilingual Indian state. The official languages of the state are English, Nepali, Sikkimese and Lepcha. Additional official languages include Gurung, Limbu, Magar, Mukhia, Newari, Rai, Sherpa and Tamang for the purpose of preservation of culture and tradition in the state. English is taught in schools and used in government documents. The predominant religions are Hinduism and Vajrayana Buddhism. Sikkim’s economy is largely dependent on agriculture and tourism, and as of 2014 the state had the third-smallest GDP among Indian states, although it is also among the fastest-growing.
Sikkim accounts for the largest share of cardamom production in India, and is the world’s second largest producer of the spice after Guatemala. Sikkim achieved its ambition to convert its agriculture to fully organic over the interval 2003 to 2016, the first state in India to achieve this distinction. It is also among India’s most environmentally conscious states, having banned plastic water bottles “in any government functions and meetings” and polystyrene products (throughout the state).
Nestling in the Himalayan mountains, the state of Sikkim is characterised by mountainous terrain. Almost the entire state is hilly, with an elevation ranging from 280 metres (920 ft) in the south at border with West Bengal to 8,586 metres (28,169 ft) in northern peaks near Nepal and Tibet. The summit of Kangchenjunga, the world’s third-highest peak, is the state’s highest point, situated on the border between Sikkim and Nepal. For the most part, the land is unfit for agriculture because of the rocky, precipitous slopes. However, some hill slopes have been converted into terrace farms.
Numerous snow-fed streams have carved out river valleys in the west and south of the state. These streams combine into the major Teesta River and its tributary, the Rangeet, which flow through the state from north to south. About a third of the state is heavily forested. The Himalayan mountains surround the northern, eastern and western borders of Sikkim. The Lower Himalayas, lying in the southern reaches of the state, are the most densely populated.
The state has 28 mountain peaks, more than 80 glaciers, 227 high-altitude lakes (including the Tsongmo, Gurudongmar and Khecheopalri Lakes), five major hot springs, and more than 100 rivers and streams. Eight mountain passes connect the state to Tibet, Bhutan and Nepal.
Sikkim is situated in an ecological hotspot of the lower Himalayas, one of only three among the ecoregions of India.  The forested regions of the state exhibit a diverse range of fauna and flora. Owing to its altitudinal gradation, the state has a wide variety of plants, from tropical species to temperate, alpine and tundra ones, and is perhaps one of the few regions to exhibit such a diversity within such a small area. Nearly 81 per cent of the area of Sikkim comes under the administration of its forest department.
Sikkim is home to around 5,000 species of flowering plants, 515 rare orchids, 60 primula species, 36 rhododendron species, 11 oak varieties, 23 bamboo varieties, 16 conifer species, 362 types of ferns and ferns allies, 8 tree ferns, and over 900 medicinal plants. A variant of the Poinsettia, locally known as “Christmas Flower”, can be found in abundance in the mountainous state. The Noble Dendrobium is the official flower of Sikkim, while the rhododendron is the state tree.
Orchids, figs, laurel, bananas, sal trees and bamboo grow in the Himalayan subtropical broadleaf forests of the lower altitudes of Sikkim. In the temperate elevations above 1,500 metres (4,900 ft) there are Eastern Himalayan broadleaf forests, where oaks, chestnuts, maples, birches, alders, and magnolias grow in large numbers, as well as Himalayan subtropical pine forests, dominated by Chir pine. Alpine-type vegetation is typically found between an altitude of 3,500 to 5,000 metres (11,500 to 16,400 ft). In lower elevations are found juniper, pine, firs, cypresses and rhododendrons from the Eastern Himalayan subalpine conifer forests. Higher up are Eastern Himalayan alpine shrub and meadows and high-altitude wetlands, which are home to a wide variety of rhododendrons and wildflowers.
The fauna of Sikkim include the snow leopard, musk deer, Himalayan tahr, red panda, Himalayan marmot, Himalayan serow, Himalayan goral, muntjac, common langur, Asian black bear, clouded leopard, marbled cat, leopard cat, dhole, Tibetan wolf, hog badger, binturong, and Himalayan jungle cat. Among the animals more commonly found in the alpine zone are yaks, mainly reared for their milk, meat, and as a beast of burden.
The avifauna of Sikkim include the impeyan pheasant, crimson horned pheasant, snow partridge, Tibetan snowcock, bearded vulture and griffon vulture, as well as golden eagles, quails, plovers, woodcocks, sandpipers, pigeons, Old World flycatchers, babblers and robins. Sikkim has more than 550 species of birds, some of which have been declared endangered.
Sikkim also has a rich diversity of arthropods, many of which remain unstudied.  Some of the most understudied species are Sikkimese arthropods, specifically butterflies. Of the approximately 1,438 butterfly species found in the Indian subcontinent, 695 have been recorded in Sikkim. These include the endangered Kaiser-i-hind, the Yellow Gorgon and the Bhutan Glory.