In the eleventh century, in 1066 to be precise, the Normans conquered England, and during the next few centuries London became one of the most powerful and prosperous cities in Europe. The East End benefited from this, and because there were fewer restrictions there than in the city itself, plenty of newcomers settled there from abroad, bringing their skills as workers, merchants or money-lenders during the next few hundred years. In the sixteenth century the first dock was dug where ships were constructed, eventually making the East End the focus of massive international trade. And in the late sixteenth century, when much of the rest of England was suffering economically, a lot of agricultural workers came to the East End to look for alternative work. In the seventeenth century, the East End was still a series of separate, semi-rural settlements. There was a shortage of accommodation, so marshland was drained and built on to house the large numbers of people now living there. By the nineteenth century London was the busiest port in the world, and this became the main source of employment in the East End. Those could afford to live in more pleasant surroundings moved out, and the area became one where the vast majority of people lived in extreme poverty, and suffered from appalling sanitary conditions.