Not comparatively, mind you, though the distinction is slight in this case.
This medieval Slovene glory referred, on the one hand, to the notion that the Slovene ethnic territory of the 9th century was three times bigger than it is today, extending to the north as far as the Danube between Vienna and Linz and even across the river. This belief has survived into the present and until recently nobody has thought of questioning it and consigning it the place where it really belongs—the dustbin of historical myths. (Štih 2010, p. 17)
I cannot help thinking of Korean assertions about Koguryŏ (Goguryeo) and especially Gojoseon in this vein, regarding the extreme difficulty of discerning not only the linguistic landscape of the region before the tenth century (and especially before the seventh), but also the political and socioeconomic landscapes. If speakers of a Korean language held part of what’s now Manchuria, that is, as seems likely, it doesn’t mean that Silla’s ultimately failed attempt to subsume that area was a thwarted reunion, nor does the subsequent translatio imperii to the Khitans indicate that they caused a Korean state to vanish. And we know already that premodern Korean-speakers comprised multiple ethnic groups; it’s a common nationalizing fallacy to pretend that one language == one gens == one shared history. [ETA There's a flip side to these musings: given how subjectively the fragments of evidence may be interpreted, if it really were the case that an ethnic Korean-in-the-narrow-sense polity existed from the peninsula's tip to a considerable stretch north, how could it be proven? The Slovene versus Slavic distinction pertains, in particular---there were Slavs by the Danube and north of it, but not Slovenes, in Štih's example.]
And, as ever, I wonder how scholars writing in East Asian languages treat these issues, because I cannot read their work. Štih’s volume is itself a translation into English of eighteen essays he’s published across his career, and I am reading it after seeing its TMR review because we scholars of the Western European Middle Ages know dangerously little about anything Slavic. (I have UCLA’s copy via inter-library loan, FWIW.)
Štih, Peter. The Middle Ages between the Eastern Alps and the Northern Adriatic: Select Papers on Slovene Historiography and Medieval History. Leiden: Brill, 2010.