The Greater Himalaya complex of mountains includes the Himalayas and some related ranges. On the eastern end of the Himalaya proper is the Hengduan Range, which includes the Three Parallel Rivers National Park in China. On the west, the Himalayas connect to a large area of high ground called the Pamir Knot, and several other ranges extend in various directions from the knot. The main ones are the Karakoram, running east parallel to the Himalaya and north of it, the Hindu Kush running southwest, and the Tien Shan Range running north.
Wikipedia's list of the highest mountains in the world consists entirely of 109 mountains in the greater Himalaya region, all over 7200 m (23,622 feet) and including 14 over 8000 m. Eight of the ten tallest — including the highest of all, Mount Everest at 8848 m — are in the Himalayas region of Nepal.
For comparison, neither Western Europe nor the lower 48 US states have anything that reaches 5,000 m. In the Himalayas, some of the passes and inhabited plateau areas are around 5000. On the climbers' list of Seven Summits, the highest mountains on each continent, only two besides Everest are over 6000 — Denali in Alaska at just under 6200, and Aconcagua, the highest peak of the Andes and the tallest mountain outside the Himalayan region, at just under 7000. Mount Elbrus in the Caucasus is Europe's highest peak at just under 6000. In the Himalayas, peaks over 6000 are commonplace and there are dozens over 7000.
Most towns in the Himalayas can be reached by road, and some by train or plane, though many of the more rural areas require trekking and some of the trekking is quite difficult.
On the southern side most of the range can be reached via India, but western parts are reached via Pakistan or Afghanistan. Two small countries, Nepal and Bhutan, are located within the Himalayas on that side. On the north side, all of the Himalaya proper is in Tibet.
The Indian subcontinent and the rest of Asia are on different continental plates that are colliding; the Himalayas and related ranges are along the boundary of the plates. The force of the collision creates the world's highest mountains.
North of the Himalayas is the Tibetan Plateau, the world's largest and highest (over 3000 m on average) plateau. It includes all of Tibet and the Chinese province of Qinghai plus parts of several other provinces.
The Himalayas are a home to a diverse number of people, languages, and religions. Generally speaking Islam is prevalent in the west, Hinduism along the southern edge, and Buddhism in the north. While there are numerous languages spoken, Hindi or Urdu — the spoken languages are mutually intelligible, though the written forms are quite different — will take you very far, as it is understood by the majority in the Pakistani, and Indian Himalaya. In Nepal it's not very useful, but it does have significant overlap with Nepali, and therefore gives you a head start with that language.
The latitudes in the Himalayas range from almost tropical along the southern edge to about 40 north (latitude of Chicago, Beijing or Rome) in the Pamir Knot. However, Himalayan weather is more severe than in other places at similar latitudes, due to the altitude and the lack of any large body of water nearby to moderate the climate. Many of the peaks have snow atop them year round and there are many glaciers.
There is a large variation in micro-climates throughout the region; two valleys only a few miles apart but isolated by the mountains may have quite different climates because one gets more sun or they are affected differently by the wind patterns.
Flora and fauna
The diversity of wildlife in the Himalayas is huge. In the lower ranges, tigers, leopards, and the one-horned rhinoceros can be found while the higher altitudes support a smaller but more unique group of animals. These include the snow leopard, Markhor goat, argali, and red panda. Yaks are common as a domestic animal in much of the region.
The Himalayas spread across several countries. All Himalayan regions offer similar attractions, but there are interesting differences as well.
The northern Areas of Pakistan offers some of the most visually stunning parts of the Himalayas. The trekking in Northern areas is arduous, seldom without glacier crossings, and not for the inexperienced, or unprepared. Local law, and good sense, prohibit trekking without a local guide on most routes. As such it is one of the more costly parts of the Himalayas for trekking. The people in this area, while being almost entirely Muslim, are diverse, with numerous languages, and different types of Islam followed--some highly conservative, some noticeably liberal. The Karakoram Highway runs through the mountains to connect Pakistan with Western China.
Azad Kashmir encompasses the lower part of the Himalayas which is considered one of the most beautiful part of Himalayas due to lush green and scenic valleys. Parts of Azad Kashmir along the border (India-Pakistan line of control) with India are off limits for foreigners.
Pashton-dominated and conservative, much of which would be unwise for tourists to visit but the western and northern parts which encompass the lower part of the Himalayas are an exception which provide fascinating and scenic landscape and unusual beauty.
- Jammu and Kashmir With its mountains and lakes, this was a popular destination with travelers until the conflict escalation between Pakistan and India. While Srinagar is reasonably safe, much of the countryside is dangerous and some of it, especially along the border, is off-limits.
- Ladakh is the important exception to this, an independent kingdom for centuries and still with its own culture but now administratively part of Kashmir. Offering much in the way of sight-seeing, and trekking it's not to be missed.
- Himachal Pradesh A pleasant, laid back, predominantly Hindu state, with a Tibetan Refugee population; popular with tourists.
- Uttaranchal Another state of India, the source of the Ganges, it has a number of pilgrimage sites.
- Uttar Pradesh A state that is mainly on the plains but borders the mountains, and includes some.
- Sikkim Wedged between, Nepal, Bhutan, China and West Bengal, Sikkim has many Buddhist monasteries and related sights. Trekking here is limited due to the closeness of the border with China. You must take a guide and go as a group, and there are a very limited number of routes.
- West Bengal Most of the province is on the plains, a populous region of farming and industry, but the northern edge extends into the mountains. The area around Darjeeling is popular as a tourist destination.
- Arunachal Pradesh At the northeast extreme of India and seldom visited by tourists, this state is a fascinating mix with a large tribal population; people follow, Animist, Hindu, Buddhist, and Baptist Christian religious traditions.
A major tourist destination, with numerous sightseeing, trekking, and other adventure sport opportunities, Nepal has a level of tourist specific infrastructure far in advance of anywhere else in the region. Here you can trek for a month and stay in guest houses every night, and need not carry more than a change of clothes or two, and your sleeping bag. Nepal has unfortunately been suffering from a Revolutionary Maoist uprising making the country less than safe.
A fascinating little kingdom, Bhutan only issues visas to tourists on expensive group tours or to individuals who benefit the country, i.e. NGO workers, or exchange students.
The northern borders of India, Nepal and Bhutan generally follow the Ganges-Brahmanputra watershed, however the Himalaya extend north of this watershed. There are also outlying ranges rising out of the plateau northward to the Brahmaputra (or Yarlung Tsangpo as the river is called in Tibet) which are included with the Himalaya. This part of the Himalaya is less explored, often difficult of access, and has numerous unclimbed peaks.
The old Tibetan province of Kham — now split up administratively between the two Chinese provinces Yunnan and Sichuan and China's Tibetan Autonomous Region — is closely related to Himalayan areas further west in both geography (large mountains created by the same tectonic plate collision) and people (predominantly Tibetan speakers).
Himalaya is home to highest peaks on Earth and most sights relate to the mountains themselves, but because of the relative isolation of mountain valleys there is also an interesting diversity in flora, fauna and cultures. Some of the mountains are sacred to Muslims, Hindus or Buddhists and there are many monasteries, mostly Buddhist.
Trekking is the most popular activity, with a wide selection of possibilities, from deserts to jungles. It's also popular to study yoga or meditation. White water rafting is also popular in many places.
If you are not planning to do any trekking, then you will not need any special equipment, or even warm clothing as you will be able to pick up good warm clothing on entry to the region. If you do need warm clothes, don't miss the second-hand markets selling attire from wealthy nations.
If you are trekking, the equipment you will need depends on your destination, in most of Nepal you will need nothing more than a sleeping bag and a pair of boots; the Indian Himalaya offer a large number of routes that are possible to trek independently if you have a tent, stove, and all the equipment needed for unsupported trekking.
In general the Himalayas have fewer dangers than the more densely populated plains around them.
- Malaria is only an issue in the areas of low elevation, as the mosquito that carries the disease is not able to live at higher elevations. Take precautions when traveling through areas of lower elevation, especially the neighboring plains.
- Altitude sickness is a worry, with many of the passes in the Himalaya being over 5000 m. Increase your elevation as slowly as possible, avoid flying from a low elevation to a high one, limit your physical activity; and drink lots of liquids after gaining altitude. Altitude sickness is unpredictable, and may strike people who haven't had problems before. Give yourself lots of flexibility in your plans, to avoid pushing yourself higher when you need to rest.
- Stay up to date with the news, and be willing to change your plans, when going to places such as Kashmir, that are facing armed uprisings.
- Traffic on the narrow roads is often frightening, but due to the slow speeds is less likely to result in fatalities than on the roads of the plains.
Flights out of the Himalayas are often cancelled due to bad weather, be sure to give yourself at least a few days before needing to catch a connecting flight.