The Czechs have always been the Slavic nation living farthest to the west. With a population of 6,500,000 in 1910, they were the third strongest ethnic group in the monarchy, although they formed only 12.7 percent of its total population. At that time the Czechs, as well as the Magyars, Croats, and Slovenes, with a few minor exceptions, lived only within the Habsburg empire. In the largely agricultural countryside between the Czech and German populations there was a clearly demarcated line which changed only rarely. Strong nationalists on both sides of this boundary, however, paid much attention to even the slightest changes in it. The dividing line between the Czechs and the Slovaks, which was the same as the frontier between the Czech lands and Hungary, was also stable. It cannot be said that this line actually amounted to a language barrier, since dialects which were nearly the same were spoken on both sides of the Morava River. The gradual transition between Czech and Polish dialects in Silesia, together with the strong westward Polish migration, however, made the nationality frontier between the Czechs and Poles relatively unstable.