Liberation war and independence
British Indian Empire in 1947, Bangladesh was integrated in Pakistan which was known as
East Bengal until 1955 and thereafter as
East-Pakistan following the
One Unit program.
Bilateral relations between the two wings grew strained over the lack of official recognition for the
Bengali language, democracy, regional autonomy, disparity between the two wings, ethnic discrimination, and the central government's weak and inefficient relief efforts after the
1970 Bhola cyclone, which had affected millions in East Pakistan. These grievances led to several political agitations in East Bengal and ultimately a fight for full independence. In March 1971, the
Pakistan Armed Forces began "
Operation Searchlight," which targeted intellectuals, political activists,
Hindus and other minorities.
 The number of people killed by Pakistani forces remains disputed, with estimates ranging from 300,000 to 3 million.
 About 8-10 million people became refugees in India.
 Many Bengali policemen and soldiers mutinied and nationalists formed a guerrilla force, the
Mukti Bahini with Indian and Soviet Union support. When a declared war broke out between East Pakistan and West Pakistan in December 1971, the joint forces of
Indian Army and Mukti Bahini later known as Bangladesh Armed forces defeated Pakistani forces in East Pakistan and the independent state of Bangladesh was created.
1974–2012: Establishment and growth of bilateral relations
Pakistan Peoples Party (PPP) led by
Zulfikar Ali Bhutto, who had been the main political opponent of
Sheikh Mujibur Rahman, came into
power in the aftermath of Bangladesh's separation from Pakistan. A heavy lobbying staged by Pakistan, other states such as the
People's Republic of China,
Saudi Arabia and some other Middle Eastern nations, refused to recognize Bangladesh. In 1972, Pakistan left the
Commonwealth of Nations after it extended membership to Bangladesh. For its part, Bangladesh demanded an apology from Pakistan for
war crimes committed by the
Pakistani military and reparations. Bangladesh's development of
close ties with India, which had played a role in securing its independence, also angered Pakistan.
On the issue of Bangladesh's application for membership to the UN, China, on Pakistan's request, exercised its veto power for the first time to stall the move, which helped Pakistan to secure in a bargain the release of its POWs and the return of troops to their prewar positions.
In 1974, the relationship between Bangladesh and Pakistan thawed. Sheikh Mujibur Rahman withdrew the bans on some pro-Pakistan organisations that had operated before Bangladesh's independence. Rahman visited
Lahore for an
Organization of the Islamic Conference summit, and in return the
Parliament of Pakistan authorised Bhutto to extend recognition to Bangladesh.
 In June 1974, Pakistani Prime Minister
Zulfiqar Ali Bhutto visited Bangladesh and paid homage to Bangladesh's war memorial at
 Both nations discussed an agreement in 1975 in which Bangladesh agreed to take up half of Pakistan's pre-1971 external reserves provided Bangladesh received half of the country's pre-1971 assets and credit went unresolved.
Relations improved considerably under the governments of
Ziaur Rahman and
Hossain Mohammad Ershad in Bangladesh, which had grown more distant from its usual allies, like India and Russia.
 Five Pakistani heads of government have made official visits to Bangladesh since the 1980s and numerous trade and cultural agreements have been signed.
 Common concerns over terrorism have influenced strategic cooperation leading to a gift of several
F-6 fighter aircraft to the
Bangladesh Air Force in the late 1980s although there was no serious effort to maintain them as they were later left to be destroyed by a cyclone.
 Trade between the two countries currently stands at $340 million which was described by the Deputy High Commissioner of Bangladesh, Ruhul Alam Siddique as 'negligible when taking into account the combined population' (of both countries). Areas he hoped would induce investment from Pakistan to Bangladesh included the textiles and energy sectors.
In 1985, Pakistani President
Muhammad Zia-ul-Haq visited the Bangladeshi war memorial, and said "Your heroes are our heroes."
 Bangladeshi President Erhsad visited Islamabad in 1986.
 In 1998, Prime Minister
Sheikh Hasina visited Pakistan.
 In July 2002, Pakistani General
Pervez Musharraf also visited the war memorial and said "Your brothers and sisters in Pakistan share the pain of the events of 1971."
2013: War crimes tribunal
In December 2012, several members of
Pakistan Parliament sought a Parliamentary resolution that would apologize to Bangladesh for the 1971 atrocities. This initiative was also supported by
In December 2013, following the execution by Bangladesh of Bangladeshi Islamist leader,
Abdul Quader Molla, dubbed the "butcher of Mirpur"
 for war crimes, the
National Assembly issued a statement condemning execution, claiming it to be politically motivated.
Interior Minister expressed sadness that Molla was executed for his "loyalty towards Pakistan".
Following Pakistan's reactions, Bangladesh summoned the Pakistan envoy, conveying its displeasure at Pakistan's interference in its internal matters.
 Bangladesh conveyed its displeasure at the National Assembly statement, Punjab Provincial Assembly statement, as well as the remarks by Pakistan's Interior Minister.
Protesters in Bangladesh took the streets to express their displeasure by marching towards the Pakistan High Commission in Dhaka.
Bihari refugees issue
An issue of continuing controversy is the status and return of
Biharis, also called
 to Pakistan.
 Numbered around 540,000, these communities had migrated to what became East Pakistan from the Indian state of
Bihar after the
partition of India in 1947.
 During the
liberation war, these communities supported the
Pakistani government and later wanted to emigrate to Pakistan, which stalled and hesitated.
 By 1982 about 127,000 had been repatriated, leaving about 250,000 people still demanding repatriation.
 In 1985 there was some progress in this area when
Zia-ul-Haq agreed to accept the "stranded Pakistanis."
 In a 2002 visit to Bangladesh, Pakistani president
Pervez Musharraf signed numerous bilateral agreements but said he could not allow the emigration of Biharis to Pakistan for the time being.
Defense cooperation improved considerably under the military regimes of Ziaur Rahman and Hossain Mohammad Ershad in Bangladesh, which had grown more distant from its war ally, India. Common concerns over India's regional power have influenced strategic cooperation leading to a gift of several squadrons of F-6 fighter aircraft to the
Bangladesh Air Force in the late 1980s.
Bilateral trade between the two countries has been growing slowly over the past years. During the eleven-year period between 2000–01 and 2010–11, Pakistan export to Bangladesh grew at an average annual rate of 27.6 percent and imports from Bangladesh grew at the rate of 9.2 percent. The total value of trade (export plus import) between the two countries in 2010-11 was about $983 million. To give a boost to bilateral trade between Pakistan and Bangladesh both countries have decided to finalise a bilateral Free Trade Agreement. FTA will pave the way for opening trade opportunity and will help expansion of trade between the two countries.
The two way trade current stand at $340 million which was described by the Deputy High Commissioner of Bangladesh, Ruhul Alam Siddique as 'negligible when taking into account the combined population' (of both countries). Areas he hoped would induce investment from Pakistan to Bangladesh included the textiles and energy sectors.