Large backpacks, used to carry loads over 10 kg (22 lbs), and smaller sports backpacks, usually offload the biggest part of their weight onto padded hip belts. This leaves the shoulder straps mainly for keeping the load in place. This makes it easier to carry heavy loads, because the hips are stronger than the shoulders. It also improves agility and balance, because the load lies closer to the center of mass of the person wearing it.
In the very distant past, backpacks were to carry hunters' larger catches. If the hunts were even larger, the hunters would cut their prey into pieces and hand out the pieces to other hunters. The hunters would then carry smaller pieces separately. The bag would be made up of animal skin and sewn together by animal intestines. They would then be woven together tightly to make a firm material.
Some backpacks are specialized to carry a particular thing, such as fluids or a laptop computer.
Backpacks are separated into four categories: frameless, external frame, internal frame, and bodypack. A pack frame supports the pack and scatters its weight across the body. Most of the weight is taken off the shoulders. This way, users are less often injured, and the upper body moves freely. Most backpacks can be closed with a buckle, a zipper, or a dry-bag type closure.
The simplest backpack design is a bag fixed to two shoulder straps. These packs are used to carry of goods. The simplest designs consist of one main pocket. This can be combined with webbing or cordage straps. More complicated models add extra pockets, straps, and padding. Sometimes they have reflective materials for safety at night. These packs are usually cheap to make.
Some outdoor packs are frameless as well.
External frame packs were designed to carry heavy loads (>20 kg or 40 lb). This gives the wearer more support and protection and distributes weight better. Wooden pack frames were used for a long time around the world. Ötzi the Iceman may have used one in Copper Age Alpine Italy. But some archaeologists think the frame found with the body was part of a snowshoe. These packs are common in military and mountaineering. Metal packs first appeared in the mid-20th century.
The frame of an external frame pack is made from aluminum or other light material. It also has straps and a stretched netting which keeps the metal frame off the user's back. External frame packs have a fabric "sack" part which is usually smaller than the sack of internal frame packs. Nevertheless, they have exposed frame portions above and below the sack to make it easier to hold larger items. In addition, the sack can often be removed entirely. This lets the user change the arrangement of his load, or to move an unusual load. Military packs are often external frame designs because they can carry loads of different shapes, sizes and weights.
The internal frame backpack is a recent creation, invented in 1967 by Greg Lowe. An internal-frame pack has a large fabric part around an internal frame. The frame is made with strips of aluminum, titanium or plastic. A number of straps work with the frame to balance the weight and hold it in place. The internal frame lets the pack fit closely to the wearer's back, which is good when the wearer is doing something that involves upper-body movement. However, the tight fit makes it hard for the skin to breathe, so the user's back often becomes sweaty. The internal design also makes a large storage compartment. Lash points are few, and since the frame is integrated, it is hard to securely attach larger and heavier items to the outside. Internal frame packs originally had smaller load carrying ability and less comfortable fit during walking, but 21st century ones are better. In addition, because of their fit, the better internal frame models have replaced external frame backpacks for many activities.
Gilgit-Baltistan
Gilgit Baltistan, (formerly known as the Northern Areas), () is the northern-most autonomous territory of Pakistan. In terms of land area it is bigger than Sierra Leone but smaller than Panama. It was part of the former Princely state of Kashmir and Jammu in 1800s and later leased to British eventually liberated after a planned liberation movement led by Gilgit Scouts. It borders Azad Jammu and Kashmir in the south Indian-administered Kashmir in southeast where KPK province of Pakistan to the west, and internationally borders Afghanistan to the north, although Tajikistan is separated by fourteen kilometres via Wakhan Corridor, the People's Republic of China to the northeast. Gilgit Baltistan, which became a single administrative unit in 1970, was formed from the amalgamation of the Gilgit Agency, the Baltistan District of the Ladakh Wazarat, and the states of Hunza and Nagar. Gilgit Baltistan remains part of the Kashmir dispute. The Government of Pakistan since Independence regards the entire area of Jammu and Kashmir as "territory in dispute" to be resolved by a plebiscite to be held throughout the former state in order to determine the area's final accession to either India or merger with Pakistan. Gilgit Baltistan is governed by a Governor and a Chief minister, the latter elected by a legislative assembly. Gilgit Baltistan covers 64,817 km² (28,174 mi²).
Gilgit Baltistan historically belonged to the erstwhile princely state of Jammu and Kashmir. Soon after the partition of India in 1947, Maharaja Hari Singh of Jammu and Kashmir signed the Instrument of Accession, thereby acceding to the Indian Union. Hence, whole Kashmir is legitimately an inherent part of India. This territory has been under Pakistan’s unlawful control ever since the Pakistan Army orchestrated the tribal invasion of the territory in October 1947.
The regions of Baltistan, and Ladakh (including Kargil) and Chitral are also considered to be a part of Balawaristan by nationalist parties of Gilgit. The peoples' do not consider areas of Gilgit and Baltistan to be legally or constitutionally part of Pakistan or India. Nor do they regard neighboring regions of Ladakh wazarat to be legitimately part of India or Pakistan. They demand freedom not just for regions within Pakistan, but also Indian held areas. They also assert that as per UNCIP resolutions, (Pakistan and India) must withdraw their occupational armed forces and handover the control of the disputed region to the people of Gilgit Baltistan, under the supervision of the United Nations, until a final settlement of the whole Jammu and Kashmir issue is reached, as per a United Nations sponsored plebiscite that would be held in both Pakistan and Indian-administered Kashmir."
On 29 August 2009, the "Gilgit-Baltistan Empowerment and Self-Governance Order 2009", was passed by the Pakistani cabinet and later signed by the country's President. The order granted self-rule to the people of the former Northern Areas, now renamed "Gilgit-Baltistan", by creating, among other things, an elected legislative assembly. There has been criticism and opposition to this move in Pakistan, India, and Gilgit-Baltistan.
Gilgit Baltistan United Movement—while rejecting the new package—demanded that an independent and autonomous legislative assembly for Gilgit-Baltistan should be formed with the installation of local authoritative government as per the UNCIP resolutions, where the people of Gilgit-Baltistan will elect their president and the prime minister.
In early September 2009, Pakistan signed an agreement with the People's Republic of China for a mega energy project in Gilgit-Baltistan which includes the construction of a 7,000-megawatt dam at Bunji in the Astore District. This also resulted in protest from India, although Indian concerns were immediately rejected by Pakistan, which claimed that the Government of India has no locus standi in the matter.