The Himalaya are a range of mountains in Asia, most correctly defined as stretching from the Indus river in Pakistan, through India, Nepal, Bhutan, ending at the Bramaputra River in India. This is often extended to include the Karakoram, the Hindu Kush, and other minor ranges extending from the Pamir Knot, as these mountains are continuous with the Himalaya proper, and the geographical difference makes no difference for the traveller, we follow this convention here. This region includes the 14 highest mountains in the world, and over 100 peaks over 7200m.
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.
Most parts of the Himalaya are connected to the plains to the south, by bus and airplane.
The Himalaya are a home to a diverse number of people, languages, and religions. Generally speaking Islam is prevalent in the west, Hinduism in the southern ranges of the eastern Himalaya, and Buddhism in the northern ranges of the western Himalaya. While there are numerous languages spoken, Hindi/Urdu (when written, they are two totally different languages, when spoken they are nearly interchangeable) 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 as such gives you a head start with that language.
Flora and Fauna
The northern Areas of Pakistan offers some of the most visually stunning parts of the Himalaya. 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 Himalaya for trekking. The people in this area, while being almost entirely mulslim, are diverse, with numerous languages, and diferent types of Islam followed, some highly conservative, some noticabely liberal.
This highway leads North from Pakistan into Western China.
Much of Azad Kashmir is off limits for foreigners, due to the ongoing conflict with India.
This is a very conservative, largly tribal area, much of which would be unwise for tourists to visit, Peshawar is an exeption to this, and is an fascinating, accessable look at a Pashtoon city.
Picturesque forested mountains, this was a popular destination with travelers until the conflict escalation between Pakistan and India. While Srinagar is reasonable safe, don't spend time in the country-side. Ladakh is the important exception to this. Offering much in the way of sight-seeing, and trekking it's not to be missed.
A pleasant, laid back, predominantly Hindu state, with a Tibetan Refugee population; popular with Tourists.
Another state of India, the source of the Ganges, it has a number of pilgrimage sites.
Wedged between, Nepal, Bhutan, China and West Bengal, Sikkim was predominately Buddhist until the 19th century, when numerous Nepalis came. As such there are 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, there are very limited number of routes.
Seldom visited by tourist, this state is a fascinating mix, with a large tribal population, people follow, Animist, Hindu, Buddhist, and Baptist Christian religous 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.
Most sights relate to the mountains themselves, and to religious structures, Muslim, Hindu and Buddhist. Many of the most popular destinations are sights in themselves.
Trekking is the most popular activity, with a wide selection of possibilities, from desserts to jungles. It's also popular to study Yoga or Meditation. White Water Rafting is popular in many places
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 conecting flight.