http://blog.oup.com/2013/08/buddhism-be ... -division/
At the recent Association for Asian Studies (ASA) conference, four scholars, each in their own way, spoke to the constraints imposed by privileging geo-political categories as the structures by which Buddhism is apprehended, raising issues directly relevant to the discussions made here regarding the rhetorical and lexical consequences of categorizing Buddhism according to the convenient artifice of the nation-state. They propose instead to explore Buddhism in the broader context of Asian history as a civilization that introduced new social institutions and languages, established new agricultural technologies and trading relations, and transformed the environment beyond national borders and ethnic categories.
The tendency to describe the development within the boundaries of modern nation states is problematic, though this is recognized by academia generally. However, Buddhists themselves are often comfortable with describing Buddhism through the lens of nationalism (Korean Buddhism, Tibetan Buddhism, etc.) and might even actively promote a nation-specific form of Buddhism, whereas this can only be recognized as a new development of the last few decades at best, though they'll project into the past their anachronistic model.
For example in the case of "Tibetan Buddhism":
David Gray (University of Santa Clara) questions the category Tibetan Buddhism. In his essay “How Tibetan is Tibetan Buddhism? On the Applicability of a National Designation for a Transnational Tradition,” he points out that today there is no Tibet to which this label can refer. Additionally, arguably the majority of practitioners of “Tibetan” Buddhism neither are ethnic Tibetans, nor do they speak or read Tibetan. More significantly, while Tibetans considered themselves Buddhists and had a sense of Tibet as a distinct geo-political category, “they simply did not conceive of their tradition in nationalistic terms.”
What comes to mind here is how contemporary Tibetan Buddhism in the west is often intricately linked with Tibetan nationalism, going hand in hand with the Tibetan independence movement.