The fiefs of the higher class, while at first given only to the individual, became early hereditary, and hereditary succession to estates and offices generally became the rule. Primogeniture in the succession to the estates did then not as in England prevail in Germany; instead, either tenancy in common, or else equal division among the sons was practised. As a result the very many small principalities came into existence in the 14th and 15th centuries, these growing smaller and smaller by subdivision. The first to institute the primogeniture rule by law was the house of Brandenburg (in the 15th century). In addition to the class of peasants and knights, there came into existence a third class, the burghers, when, by the order of Conrad I in the beginning of the 10th century, towns were built with walls and towers for defence against the encroachments of the Huns, who endangered the eastern frontier Mark. In order to encourage the settlement of these towns, any slave moving to town was declared a freeman; and the cities became free republics; gifts of land, including forest areas, were made to the cities, and the development of industries was encouraged in every way. These cities, favored by the kings, and, having become rich and powerful, in the later quarrels of the kings with the lawless nobility, gave loyal support with money and arms. In return for their loans, the forest properties of the kings were often mortgaged to the burghers; and, failing of redemption, were often forfeited to them. In this way and through purchases the city forests came into existence. Still other property conditions arose when, under Otto the Great (960), colonization of the eastern country beyond the Elbe was pushed. In these cases, the Mark institution was absent, although the colonists did often become part owners in the king’s forest, or acquired parts of it as common property, or else secured rights of user in the nearest royal forest. By the end of the period, due to these various developments, a great variety of property conditions in forest areas had developed, most of which continue to the present time, namely royal properties, which by the end of the eighteenth century and the beginning of the nineteenth were in part to become state property; princely and lordly possessions under separate jurisdiction, with or without entail, and mostly encumbered with rights of user; allodial possessions (held independent of rent or service); municipal possessions owned by city corporations; communal properties, the remnants of the Mark; and farmers’ woodlots (Bauernwald), resulting from partitions of the Mark.