Lesmahagow formed part of the kingdom of Strathclyde, which consisted of the southern and larger portion of the district inhabited by the Celtic tribe, called by Ptolemy the Damnii.  It was occupied by teh Romans as early as the first century of the Christian era, and was included in their provice of Valentia.   Strathclyde was never so thoroughly subdued as to become a Roman territory in which established tranquillity prevailed.  It was held in subjection by a well-disciplined military force; the inhabitants enjoying a great amount of wild freedom, although the chiefs were probably obliged to pay tribute for themselves and their clan, which would consist chiefly of cattle and firewood, for it is doubtful whether the invaders were able to exact personal services.

The form of worship of these hardy Britons was probably Druidical.   Their kingdom, which varied in size at different periods of their history, had Dumbarton for its capital, known while the kingdom of Strathclyde existed as the city of Alclyd or Alclud.

When the Roman legions were withdrawn from Britons in the fifth century, the Strathclyde Britons appear to have joined a northern confederacy in an expedition against the inhabitants beyond the Northumberland wall, which induced the latter to seek for assistance from the Romans; and although a solitary legion returned to give temporary aid to the southerners, it was soon withdrawn, and the warlike Romans bade farewell for ever to the island, after having had a footing in it for five centuries.

The next struggle between the northern and southern tribes lasted for nearly two centuries with varied success, the southern men being assisted by the Saxons.   It was terminated A.D. 603, by the great victory gained by Ethelfred of Northumberland.  For nearly half a century after that date, a truce subsisted between the Saxons and the Celtic tribeees of the Scottish Lowlands.   At the close of that period, the latter began to make encroachments on the Scots of Argyleshire.   Oswi of Northumberland, who had been educated and instructed in the Christian faith among the Scots during his exile after his father's death, and who had married a daughter of the King of the Picts, came to the aid of the northern tribes.   The results was a seven year's campaign, at the close of which, Oswi, being assisted by his compatriot Penda, King of Mercia, totally defeated the Lowland Celts, when the kingdom of Strathclyde became tributary to that of Northumbria, while the more easterly portion of Scotland was divided between the Saxons and the Picts.  This state of matters continued till the year 685, when England, the son of Oswi, having quarrelled with his uncle Brudei, King of the Picts, was defeated by him, and lost all the Scottish portion of his dominions, including the right of tribute from Strathclyde, which passed to the conqueror.

For a century and a half after this event, great obscurity prevails regarding the political condition of the inhabitants of the Strathclyde district.   Constant struggles were going on between them and the more northern tribes called the Picts, the Scoto-Irish from Cantyre, the Saxons of Northumberland, and the Cruithne of Ulster.  At the death of Bede, A.D. 735, the Strathclyde Britons retained their valued possessions, but a union of Saxon and Pictish forces having taken place,  their metropolis was taken, circa 756, and the Picts and Scots having united, circa 844,  it is probable that the reguli or petty chiefs of Strathclyde were gradually overpowered, and many of them emigrated rather than submit to foreign yoke.  The more adventurous departed as emigrants to Wales, circa 890, or later, where they found a kindred race speaking a language similar to their own, and thus was the kingdom of Strathclyde broken up.  The territory which they had abandoned was re-peopled by Scoto-Irish, Anglo-Saxons, Picts, Gallowegians, and others; or, to use the language of the Inquisition of the Prince of Cumberland, nearly two centuries later, by an influx of "divers tribes of divers nations from divers parts".  It must, however, be borne in mind, that Saxon power, which had been felt in Scotland for nearly six centuries, was extinguished about the year 1020., and we find instances of Flemish families of distinction receiving grants of land in Lesmahagow and other parts of Lanarkshire in the twelfth and subsequent centuries.

Lesmahagow, in pre-parochial times, must have been clothed in many parts with timber of gigantic growth, as trees, chiefly oak, are somtimes dug out of mosses, of such dimensions as scarcely can be matched by living examples.  In the upper part the elevation is such that the face of the country would always be moorish and best suited for pasturage, but the rich valleys of the  Nethan and Clyde must have formed a fine agricultural district so soon as tillage commenced.

The territory of the Damnii was termed Y-strad-cluyd, or the warm vale of the strath ; and Merthyn, one of the oldest British bards, alludes to the orchards of Cluyd with feelings of pride.

The early inhabitants have left some remains of circular camps within what is now the parish of Lesmahagow.  On the submit of Stonebyres hill is a specimen of a small British camp with a fosse, but now much dilapidated, and difficult to examine from the dense thicket of thriving plantations growing over it.  It was only 35 feet in diameter to the outer fosse, and may have been occasionally occupied by the Roman invaders as a castellum or watch-tower, for the idea is now exploded that the Romans never occupied circular places of strength.   There was a small camp regularly constructed, of a circular form, on the farm of Draffan, having a diameter of about 60 feet, but now much obliterated.  On the summit of Boreland and Dillar Hills there was also places of strength, which may have been British or Roma n.  Nearly all the numerous cairns remained entire until the beginning of this century, when the rage for building stone "dykes" induced the proprieors to cart them away.

Cairns, karns koerns, or heap of stones, are of extremely ancient origin, and Holy Writ (Genesis xxxi. 46, 52) may be referred to in support of the assertion.   Dr Jameson traces the word to the Hebrew kern, a horn, also a hill.   One of the  most perfect specimens of these cairns in Lesmahgow parish stood at Cairn House, on the farm Skelly Hill.  It was about 50 feet high, covering at its base nearly half an acre, and tapering towards the summit.   It had been constructed with an amazing amount of toil, many of the stones weighing about a ton each.  In the centre there were stones rudely placed on edge, measuring nearly 4 feet in length by 2 in bredth, forming the sides of a rude cist or stone coffin, with a stone lid.  Ashes were distinctly visible within it, and an urn of baked clay was brought to light, but it crumbled away when exposed to the atmosphere.  Two other cairns in the same neighbourhood were demolished about the same period, but nothing remarkable was disclosed.   One the farm of Lupus, an Edward of England penny, and a stud or button of antique shape, made of cannel coal, were found when demolishing some small cairns in 1822; also a groat of Robert II.of Scotland.  These relics are now in the possession of the proprietor, J. G. M'Kirdy, Esq.  The stud resembles one represented by Wilson in his "Pre-historic Recorods" (p. 295); also in the "Archaeologia Scotica."  In Hoare's "Ancient Wiltshire" they are called "pulley beads"  Near Muirsland farm-house a cairn was removed about the year 1814.  It contained no stone or cist, but bones were found, over which had been pilled between 200 and 300 carts of stones.  Not long after, the plough turned up, on the site of the cairn, a thin gold coin, about the size of and Edward penny.  It was perforated by the finder, and worn as an appendage to his watch, but soon got worn through, and is now lost.  It was probably an early gold coin of the Scotch or English series, as the early British gold coins and the Roman aurei are all thick in proportion to their size.  At Fauld House, a large cairn was demolished about sixty years ago, which furnished about 1400 carts of stones as materials for building stone "dykes".  In the centre was a rude stone coffin, formed of stones set on edge, with a lid, and in the coffin was found a coin which unfortunately, in course of time, got mixed with others in the possession of John Smith, Esq., the proprietor.   Several were selected by the author as the oldest coins in Mr. Smith's collection, one being a Henry III. of England short cross penny, minted at Canterbury, by Hue, date circa A.D. 1216-48, and one and Edward penny.  Mr. Smith has no older coins than these in his possession, and is not aware of any which he or his father possessed having been parted with; so that the solution of the difficulty must, it is feared, remain in its present unsatisfactory state.  He is confident that his father was present when a coin was taken out of the rude stone coffin.  At one period, in consequence of the introduction of mortsafes, the grave-diggers in Lesmahagow were obliged to dig deeper than they had been acustomed to do, and it was not uncommon ot find and Edward penny near the bottom of each grave.  There is an authentic instance of the discovery of an  Edward penny (king's head in a triangle) within a cairn on the east side of Swaites hill, in the parish of Pettinain.  In the same cairn were found several flint arrow heads, which have been lost sight of; but a game keeper on the Lee and Carnwath estates, presented the Edward penny ot Mr. Sim of Cultermains.  In the Journal of the British Archaeological Association for June 1855, there is given, on the authority of H. Syer Cumng, Esq., a drawing of an arrow blade, exhumed in London in 1848, along with remains palpably of the thirteenth century; and Sir Samuel Meyrik's authority is quoted in support of the idea that such wepons were used as late as the fifteenth century.  Mr. Cuming thinks they were in use in Saxon times.