The motte-and-bailey type of castle is to be found throughout feudal Europe, but is probably more prevalent in France and the British Isles than anywhere else. We say _probably_, because there are as yet no statistics prepared on which to base a comparison.[205] How recent the inquiry into this subject is may be learned from the fact that Krieg von Hochfelden, writing in 1859, denied the existence of mottes in Germany;[206] and even Cohausen in 1898 threw doubt upon them,[207] although General Köhler in 1887 had already declared that "the researches of recent years have shown that the motte was spread over the whole of Germany, and was in use even in the 13th and 14th centuries."[208] The greater number of the castles described by Piper in his work on Austrian castles are on the motte-and-bailey plan, though the motte in those mountainous provinces is generally of natural rock, isolated either by nature or art. Mottes were not uncommon in Italy, according to Muratori,[209] and are especially frequent in Calabria, where we may strongly suspect that they were introduced by the Norman conqueror, Robert Guiscard.[210] It is not improbable that the Franks of the first crusade planted in Palestine the type of castle to which they were accustomed at home, for several of the excellent plans in Rey's _Architecture des Croisés_ show clearly enough the motte-and-bailey plan.[211] In most of these cases the motte was a natural rock. On the other hand, we are told by Köhler that motte-castles are not found among the Slavonic nations, because they never adopted the feudal system.[212] Nor are there any in Norway or Sweden.[213] Denmark has some, which are attributed by Dr Sophus Müller to the mediæval period.[214]