India had been subject to invasions from as early as the 3rd century BC, but the powerful assimilative capacity of Indian culture had absorbed the culture of the earlier invaders - the Greeks, the Huns and the Sakas. The same phenomenon did not take place in the case of the Islamic culture; and though there was some kind of absorption it was not complete. The reason for this was the attachment of each to its own religion. The Muslim religion was militant and aggressive, while the Hindu religion was spiritually tolerant indeed and flexible, but obstinately faithful in its discipline of its own principle and was standing on the defence behind a barrier of social forms. Yet, mutual contact brought about an interchange of ideas and mutually influenced each other to a great extent. Underneath the ruffle and storm of political strife, there developed a mutual respect for each other and this manifested itself in many fields.

Islamic architecture in and around Delhi retained much of the characteristics in both form and detailing of Persian Islam, with only the court at Delhi able to attract and pay the best Muslim architects and artisans from abroad. As one moves away from the main power centre, the regional Islamic satraps – whether governors of the Delhi Sultanate or newly-independent Sultan – patronized an architecture which slowly began to assume a very different identity. This identity was not constant throughout, but varied from place to place, and depended chiefly on :
a. the distance from Delhi, which determined the level of dilution of ‘pure’ Islamic principles;

b. the economic condition of the regime, responsible for the quality of finished and materials used;

c. the local artisans available in the region and their specialization and experience; and

d. local Hindu architecture, which served as direct or indirect inspiration for Muslim examples.

If the Qutb Minar merely had sinuous carving which hinted at the Hindu craftsman at work, examples further away from Delhi illustrated both a riot of carving as well as formal aspects directly influenced by Hindu architecture. The main areas that produced a substantial body of architecture and can be said to have evolved a ‘style’ of their own are Gujarat, Punjab, Bengal, Malwa, some parts of south India and Kashmir.
A fusion of cultures - Indo-Islamic Architecture

"On the one hand was the rhythmic mind of the Hindu, on the other the formal mind of the Musulman." The quote from a venerable early architectural historian serve to highlight the utter difference between Muslim and Hindu building types. There were other variations apart from the merely formal: the presence of carving in Hindu temples which was forbidden in Islam, decorative lettering on mosques and tombs which was unknown in Hindu art and architecture, the Hindu propensity for a single stone and the Muslim penchant for inlay work. However in spite of this wide gulf, over the years a certain symbiosis did come into being between Muslim designers and master-builders and the Hindu craftsmen who carried out their bidding. Both benefited from the other's knowledge and what slowly evolved was a distinct new style of architecture - Persian in inspiration but very Indian in execution. Long referred to as Saracenic, it is now more properly termed Indo-Islamic.