Recorded in a number of spellings including Mordan, Morden, Mordin, Mordon, Mordern, Murdan, Murden, and possibly others, this is an English medieval surname. It is locational and originates from Mordon, a place in County Durham. The derivation of this place name and hence the later surname, is from the Old English pre 7th century word 'mor', meaning moor or fenland, and '-dun', a hill, thus the hill in the fen country. The placename Mordon first appears on record as Murdon in the year 1050 a.d. in the book known as "The History of St. Cuthbert', and later in the Pipe Rolls of Durham in 1196, as Mordon. During the Middle Ages it became customary for people to migrate, generally to seek work elsewhere, and they would often adopt or be given as their surname, the name of the place from whence they came. Spelling being at best erratic soon lead to the development of "sounds like" spellings. Amongst the early recordings in Durham is the christening of William Mordan, on October 20th 1633 at St. Andrew's, Bishop Auckland. The first recorded spelling of the family name is shown to be that of John de Mordon. This was dated 1273, in the Hundred Rolls of Cambridgeshire, during the reign of King Edward 1st of England, 1272-1307. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.