Recorded in a wide variety of associated spellings including Sinden, Sindon, Senden, Sondon, Sonden, Sundin Sunden, and possibly others, this is an English surname. It is apparently locational from some now "lost" medieval village, probably called "Sunna-denu" or similar, and meaning the valley of the Sunna people. These were an old English tribe who probably inhabitated an area north of London in the counties of Middlesex and Hertfordshire, although this is not proven. Locational surnames are by their nature "from" names. That is to say names given to people as easy identification after they left their original homes to move somewhere else. Spelling over the centuries being at best erratic, and local accents very thick, often lead to the development of "sounds like" spellings, and even more so if the village to which the name was originally connected, had itself disappeared. This is known to have been the fate of at least three thousand such places over the past five hundred years. Early examples of the surname recording taken from surviving registers of the diocese of Greater London include: Ursula Sondon, who married Francis Yeomans at St Antholins church, Budge Row, on March 19th 1572, Joseph Senden who married Ursula Ward at St Bartholomew the Less, on February 28th 1608, and Thomas Sinden, a witness at St Saviours Southwark, on January 18th 1788, and Jane Sundin, christened at St Vincents Street Scottish church, on December 6th 1789.