Literature and music have long been a means of celebrating the cults of gods, kings and nations. In South Asia, the Bhagavad Gita, the Mahabharat and the Ramayan are early examples of this, from the Sanskrit tradition. There are of course, variations upon the general themes in different regional languages, and also local songs of praise and adulation for kings and deities. When the Turks, Persians and Afghans came to settle in India, they brought with them their own traditions of glorifying the king, such as, Firdausi's Shahnama (1010 CE). Additionally, they too, had carried with them traditions from Arabic of singing, hamd and na't and tarana in praise of their God, Prophet and saints, respectively.
Through the ages, there is ample textual, pictorial and iconographic evidence of thriving traditions of courtiers, painters, musicians and poets retained by rajas and badshahs. Their main purpose was to entertain their patrons, by eulogising them whilst heralding births, celebrating marriages and proclaiming victories. This often had little bearing on reality, as the artist would exaggerate the king's good looks, valour and generosity, no matter that the monarch was no looker, busy losing battles and taxing his subjects into penury; the painter would paint a picture of exaggerated grandeur and beauty and the poet would write in similar, inflated language.
Anyone who has attended an official function in India, Pakistan and Bangladesh will confirm the resilience of this tradition of sycophancy, as long speeches are delivered praising prime ministers and presidents, ministers, governors, petty functionaries and sundry dignitaries, while much of the state infrastructure crumbles, or extolling the virtues of artists, authors and celebrities or some literary work, painting or musical performance, regardless of the artistic or literary merit of the works in question.
The national anthems of India, Pakistan and to a much lesser extent, that of Bangladesh are rooted in this tradition of eulogising and mythologising. However, they have to be viewed in the context of the late 19th and the early 20th centuries, which saw the emergence of Indian nationalism and Hindu and Muslim nationalisms in British India, culminating in 1947, with independence and partition, resulting in the creation of Pakistan; and just 24 years later, another partition and the creation of Bangladesh, in 1971.