Why have the borders of the Czech Republic (and its predecessors, Bohemia and Moravia) remained unchanged for 700 years, when almost all other borders in Central Europe have changed drastically since?

by delta_p_delta_x

Consider this map of Europe in 1300, and this one from 1444: the one unchanging border in central Europe is that of Bohemia and Moravia.

In particular, excepting the lead up to WW2 and WW2 itself, it appears that the right-angled Czech-German border has remained unchanged since the late Middle Ages. Is this merely a retroactive application by modern cartographers of the modern Czech Republic's borders onto maps of mediaeval Europe, or has the border really stayed the same all this while? If the latter, why? What makes the Czech border so uniquely static?

dahakma

The physical map reveals that the Czech Republic is surrounded by mountain ranges and the border between the Czech Republic and Germany follows the peaks of Šumava/Böhmerwald in the south and Krušné hory/Erzgebirge in the north. The small western-most Czech region Chebsko/Egerland situated between the ranges changed its owner several times.