Danelagh, or Danelagu, in English history, the part of England subject to Danish as distinct from that subject to Anglo-Saxon law and custom. By the treaty of Wedmore (879) between Alfred the Great and Guthrun, its boundaries were defined thus: - "From the mouth of the Thames to the Lea, up the Lea to its source, thence to Bedford, and along the Ouse to Watling Street." In its greatest extent, however, it may roughly be described as extending from the Thames to the Tees, and far enough west to include the counties of Bucks, Northampton, Leicester, and Notts. But the degree of Danish influence in different parts of this district varied considerably. In Yorkshire and Lindsey, in Lincolnshire, the land was divided into ridings or trithings and wapentakes (q.v.), the latter equivalent to the Saxon hundred; no trace of this division is found in East Anglia, and it was only partial in the Midlands. The evidence of local names (e.g. the endings thorp, by, and caster) shows that the Danish settlement was far more complete in Yorkshire and Lindsey than elsewhere. It is not clear what the precise difference between Danish and Anglo-Saxon law consisted in, and there was certainly a close resemblance between their leading features. The distinction, however, is recognised as late as the reign of Stephen.