The Danes soon came over in such large numbers and so frequently, that they at last got possession of the whole of East Anglia, and became the parent-stock of the inhabitants of parts of Norfolk and Suffolk. In 1003, Sweyn or Swaine, King of Denmark, came over with his forces and, in revenge for the massacre of the Danes in the previous year, burnt Norwich and its Castle, as well as many other places. They afterwards rebuilt the city and castle, and came hither in such large numbers, that Norwich became a Danish city, with a Danish Castle, about 1011. After the restoration of the Anglo-Saxon dynasty, the city entered on a new career of prosperity, and according to the Domesday Book of Edward the Confessor, it contained 25 churches, and 1320 burgesses, besides the serfs or labourers. It was still the capital of East Anglia, with a few hundred houses, but the greater part of the area round the Castle presented only marshes and green fields. Two broad arms of the sea still flowed up the valleys on each side of the city. The whole district all around consisted of marsh, and moor, and woods, and yet uncultivated land. In 1094, Herbert de Losinga, then Bishop of Thetford, removed the See hither, and began to build the Cathedral, from which time the city increased yearly in wealth and trade. Domesday Book (1086) contains an account of all the lands and estates in England, and also of all the towns. Norwich was then next in size to York, and contained 738 families. Thetford had at the same time 720 burgesses, and 224 houses empty. Thetford, therefore, was decaying and Norwich was rising. In 1377, a census was taken of several great towns in England, and Norwich was found to contain 5300 people, for a migration hither of Flemings and Walloons, who introduced the manufacture of woollen and worstead fabrics, had increased the population. In 1575, the muster roll of men delivered to the government capable of bearing arms contained 2120 names, which would be the proportion for 15,000 people. The population in 1693 amounted to 28,881 inhabitants. In 1752 it had increased to 36,241, and in 1786 to 40,051. In 1801 it had decreased to 36,832. In 1811 the number was 37,256, and during the next ten years so large was the increase that in 1821 the number was 50,288. In 1831, when the census was taken, Norwich contained 61,116; in 1841, 61,796; in 1851, 68,713; in 1861, 74,414.