Orientalism refers to a long tradition of Western representations of the Orient as exotic and 'non-coeval' with the West.

What is Orientalism?

The term 'Orientalism'was the title of a 1978 book by Edward Said, which quickly became a landmark in contemporary cultural studies and cast the foundations of postcolonial theory. Said argued that Orientalism was a key ingredient in the ideologies underpinning colonialism and imperialism, and in that sense one of the ideological cornerstones of Modernity.

Orientalism, Said argued, consisted of a long Western history of tropes and modes of representation of the 'Orient' (in itself a construct) as exotic in terms of languages, customs, sexuality, power and religion.

But even more powerfully, Orientalism was driven by what Johannes Fabian later called 'the denial of coevalness': nonwestern people were situated outside of the Western present, as representatives of an earlier stage of human civilization.

Such earlier stages of civilization could be described by Western travelers and explorers as romantic and intriguing, even seductive and picturesque. But at the same time, such exotic factors of appeal always represented inferiority, something that demanded correction through an adjustment to Western bourgeois moral, cultural, political and social standards. 

References

Said, E. (1995 (1978)). Orientalism. Western conception of the orient. Penguin Books.