This chapter talks about the lands to the east of the Elbe and the German colonization eastwards. During the later Middle Ages, from the twelfth century onwards, rural economy of Central and North-eastern Europe was transformed, mainly as a result of German immigration. Existing developments were caught up and absorbed into the transformation. But the East German rural colonizing process, which gave direction, form and power to it, was only part of the wider so-called German East Movement. The internal colonization of Germany had furnished varying, but well-tested, types of field, of village and of law. Urban life had gradually developed to a point at which the main lines of town layout and town law were established. Surveying the course of events in the agrarian history of the lands east of the Elbe from the twelfth to the fourteenth century, what first strikes one is the extraordinary extension of the cultivated area, which was accompanied by a growth of population.