Nationalism is an ideology that holds that a nation is the fundamental unit for human social life, and takes precedence over any other social and political principles. Nationalists see nations as an inclusive categorization of human beings - assigning every individual to one specific nation. In fact, nationalism sees most human activity as national in character. Nations have national symbols, a national culture, a national music and national literature; national folklore, a national mythology and - in some cases - even a national religion. Individuals share national values and a national identity, admire the national hero, eat the national dish and play the national sport. Nationalists define individual nations on the basis of certain criteria, which distinguish one nation from another; and determine who is a member of each nation. These criteria typically include a shared language, culture, and/or shared values which are predominantly represented within a specific ethnic group. 
Nationalism is a concept that imposes unity based on ethnicity and tribalistic ties, whereas Islam does not impose but rather calls for unity based on a person’s ideology. Therefore, according to Islamic principle, an individual has the right and the freedom to choose whichever group he/she wishes to be associated with based on his/her ideology. As a universal religion, Islam is nominally opposed to any categorisation of people not based on one's beliefs. Islam condemns the division of mankind on the basis of blood and territory in national and racial units, and grants no authenticity to national and racial differences. Its only test of individual worth is chastity, belief, faith and good deeds.
Islam promotes a strong feeling of community among all Muslims, who collectively constitute the Ummah. A common ideology is the basis of the unity of the Islamic Ummah, not race, country, language or even culture. The goal of nationalism is to create national units, whereas the goal of Islam is universal unity. To nationalism what matters the most is loyalty and attachment to the homeland, whereas to Islam, it is God and religion. Nationalism gives authenticity to geographical boundaries and racial distinctions, whereas Islam negates them. Nationalism inclines to limitation and race, but Islam assumes a universal outlook. Nationalism attaches value only to the historical traditions, culture, civilization, ideas and historical figures of its own nation, but Islam's vision goes beyond the frontier, race, tribe and nation . These are the reasons why nationalists seek separation from Islam a condition for nationalism to succeed, even if they do not utter it. Their acts reveal their hatred towards those who seek Islam.
It should be noted that at the advent of Islam and the Islamic revolution, the only social and political organizations of the pre-Islamic Arabs were the tribe, race and language which were used as measures of superiority or inferiority. Blood and tribal bond was the basis of unity, a rough and raw form of modern nationalism and racism. Language, too, was regarded as a sign of superiority and for this reason, the Arabs considered non-Arabs as “Ajam", which means dumb .
The Prophet (s) who founded the classless and universal society of Islam, actually brought various nations together and removed their tribal hues. At a gathering of three Muslims from three countries, namely Salman from Pars, Soheib from White Romans and Bilal from Black Ethiopia, an Arab named Gheys-bin- Motateba entered and addressed the above as 'foreigners'. The Prophet (s) said in anger: “Your father is the same and your religion is the same, and the Arabism of which you seem to be proud belongs neither to your father, nor to your mother (meaning Adam and Eve are the parents of all of you)". Then he declared: “He, who propagates the creed of tribal solidarity or fights for its sake or offers his life for it, is not of us." [Abu Da'wud]
And in another Hadith, the Messenger of Allah (PBUH) referring to nationalism and racism said: "Leave it, it is rotten."
Also, the Messenger of Allah (PBUH) said,
"Undoubtedly Allah has removed from you the pride of arrogance of the age of Jahilliyah (ignorance) and the glorification of ancestors. Now people are of two kinds. Either believers who are aware or transgressors who do wrong. You are all the children of Adam and Adam was made of clay. People should give up their pride in nations because that is a coal from the coals of Hell-fire. If they do not give this up Allah (swt) will consider them lower than the lowly worm which pushes itself through Khara (dung)." [Abu Dawud and Tirmidhi]
Various incidents narrated in different hadiths demonstrate that tribal ties have no place in Islam. Muslims are commanded to stick together and not to disassociate themselves from each other just because they come from different tribes. The Messenger of Allah (PBUH) also said,
"The believers, in their love, mutual kindness, and close ties, are like one body; when any part complains, the whole body responds to it with wakefulness and fever." [Muslim],
"The faithful are like one man: if his eyes suffer, his whole body suffers." [Muslim],
"An Arab is no better than a non-Arab. In return, a non-Arab is no better than an Arab. A red raced man was not better than a black one except in piety. Mankind are all Adam's children and Adam was created out of clay." [Al-Bukhari and Muslim, on the authority of Abu Musa]
Meaning that the Muslims, whether they are of Chinese, African, European or Asian origin, are one Ummah and they cannot be separated from each other. No tribalistic ties should ever break their unity. It should be noted that the Constitution of Medina
, an early document said to have been negotiated by Muhammad (PBUH) in AD 622 with the leading clans of Medinah, explicitly refers to Jewish and pagan citizens of Medinah as members of the same Ummah.
When East Pakistan broke away from the main Western part of the country to form Bangladesh in 1971, it was in opposition to the notion that all Muslim areas of former British India should unite in one state. The Awami League, which led the struggle for independence, grew out of the Bangla language movement, and was based on Bengali nationalism, not religion. At the same time, independent, secular Bangladesh became the only country in the subcontinent with one dominant language group and very few ethnic and religious minorities. It should be noted that, in 1971, apart from Islamists many hardline socialists were also opposed to the idea of a separate Bengali state in Bangladesh, which they branded as “bourgeois nationalism.”
After the war of liberation in 1971, myth-making attempts have been made to project the groups in power and exclude others from the process. The list of exclusion is very long. There is no place for Maulana Akram Khan, Abul Qasim Fazl Haq, and Hussain Shaheed Suhrawardy as they were the products of pre-Partition politics and contributed nothing to Bangladesh. Even Maulana Bhashani was pushed outside the pail of the new history and his role marginalized. Instead, Mukti Bahini became the main force that fought bravely against the Pakistan army and successfully liberated the country. Atrocities and genocide of the Pakistan army emerged as the second element in mobilizing the people emotionally in order to convince them that freedom was not cheap and people paid a heavy price for it. Mujib emerges as the great leader who led his people through all ups and downs. Mujib and his party took full advantage of the situation to assume total power. Soon the sacrifices and atrocities were forgotten and the people were denied participation in the power structure. Rakshi Bahini, a praetorian force, was used to silence the opposition. The leftist politicians were marginalized, bureaucracy became dominant, and the personality cult of Mujib was established. To keep the nation united, violence was permitted. Thus ended the era of romantic nationalism and the hope of the people for a better future collapsed. 
It was decided to make 1971 as a starting point of the new history. This raised the question: how then should Bangladesh nationalism be defined? If language becomes the basis of nationhood, how should West Bengal, which is now a part of India, be treated? To extricate themselves from this paradox, the historians chose to deny Bengali nationalism and instead promote Bangladeshi nationalism. This has consequently brought back religion as an element in the construction of Bengali national identity. 
Today, following an initial brutal secular dictatorship run by the original "fathers for freedom," Bangladesh is a more economically diverse state with good relations with other Muslim countries. One where the majority of the people are in-favor of an Islamic lifestyle and want to see a sincere effort to abide by it within strong institutions.
2. Islam and Nationalism by Dr. Ali Mohammed Naqvi
3. Bangladesh and its Nationalism by Mubarak Ali