The border separates Bohemia and Moravia. The joke of historians was taken up by politicians
Three years ago, when two historians from Brno secretly painted white lines on the main roads near the villages of Vendolí and Opatovec in the Svitav region to mark where Moravia begins and Bohemia ends, it seemed like a good joke at first. They didn’t laugh for too long, and the police started investigating them for the offence of damaging someone else’s property and threatened them with punishment. But politicians seized on the idea. But the whole fiasco eventually came to nothing. The Pardubice Region, where the two marked places fall and which lies on the historical border of both countries, finally accepted it as an idea worth following and, after negotiations with the Moravian National Municipality, installed eight border signs with the inscription Historical Border of Bohemia and Moravia.
Source : https://www.idnes.cz/zemske-hranice-cech-a-moravy