The place-names of Scotland fall into two great divisions, Celtic and Teutonic, representing the types of languages which have been spoken over the whole or a part of the country within historic times. Of these the Celtic division is the older and the larger. Teutonic names were introduced first by the Angles who settled in the north-east of what is now England, and after long struggles got a firm footing between Tweed and Forth in the early part of the seventh century. Thence English names have spread with the growing influence of the language, and are still spreading. A second important source of Teutonic influence was the great Norse occupation of the north and west which began about two hundred years later. On the east coast, the southern limit of Norse occupation, as indicated by the place-names, was the Beauly valley, where we have Eskadale, O.N. eskidalr, ash-dale. On the west, the islands are full of Norse names, and on the western mainland they appear with varying frequency from Cape Wrath to the Firth of Clyde. So far there has been no systematic study by any competent scholar of the English names, but a good deal of sound work has been done on the Norse element.

I have said that the Celtic names are older than the English or the Norse, but even they do not necessarily form the very oldest stratum. Scotland was inhabited long before any man of Celtic speech set foot in Britain, and that the pre-Celtic population was by no means wiped out is proved by the fact that their descendants are still plentiful. The approximate date of the Celtic conquest has been much discussed; the present tendency is to put it later than was once the fashion, and it would be certainly rash to ascribe the conquest of Scotland to a period much earlier than the fourth century B.C.[The comparative lateness of the Celtic conquest is confirmed by the fact that the remains of Celtic art in Great Britain and Ireland belong almost entirely to the later or La Tene period, which is reckoned to begin abut B.C. 400. Objects assigned to the later part of the preceding or Hallstatt period have been found in England]. When we consider further that the Celts, when they did come, formed rather a military aristocracy than the staple of the population, it need cause no surprise if we find some ancient names difficult to explain from Celtic sources. It is well to note that the people of these islands never called themselves Celts, nor are they ever so called by the classical writers. The term was unknown in native literature till it was introduced in quite recent times.

As applied to language the term Celtic, like the term Teutonic, covers more than one group. There are now, and probably were in prehistoric times, many dialects, but all fall under one or other of two great groups, differentiated most readily (but by no means wholly) by their treatment of the primitive Indo-European qu sound, the sound heard approximately in equal, or in Latin equus. One group retained this sound, making it later into c hard or c aspirated (ch). The other turned it into p. The former, called for convenience the Q-group, is represented now by Gaelic in its varieties of Irish, Scottish, and Manx. Traces of qu in continental Celtic are very slight; a possible instance is Sequana, the Seine. The other, or P-group, in early times included Gaulish and Old British; it is now represented by Welsh, Cornish (extinct), and Breton. The following examples illustrate the difference :

This difference of treatment is not confined to the Celtic languages. It is seen to some extent as between Latin and Greek, e.g. Lat. sequ-or; Gr. epomai. It is a feature of dialects within Latin, e.g. Lat., Quintus, Quinctius; Samnite, Pontius; Umbrian and Oscan, Pompeius (compare Welsh pump). It is also found dialectically within Greek, e.g. Attic pous, Ionic kous.

Celtic of both groups has the important characteristic that it has dropped Indo-European p initially and between vowels ; in other positions this original p has been modified. Thus we find :

Similarly, Lat. piscis, G. iasg, fish; Lat. parcus, G. airc, penury. It follows that no genuine native Gaelic word contains p unless as the result of later changes. The p of Gaulish, Welsh, etc., represents an original qu.

Our knowledge of British is derived from inscriptions on coins and from names of persons and places recorded by the classical writers. Goidelic – the usual term for proto-Gaelic – is known from the Ogham inscriptions on stones, of which there are about 300 in Ireland, about 30 in Wales, 5 in Devon and Cornwall, 1 in Hampshire, and 17 in Scotland. Both British and Goidelic were fully-inflected languages, with stems and case-endings similar to those of Latin. By degrees certain changes took place, by which the ancient forms were converted into the earliest stage of their respective modern forms, that is to say into Old Welsh and into Old Irish. This change was of course gradual, and in its main features was probably completed by about A.D. 550, though learned men no doubt retained a knowledge of the old forms long after they had become obsolete in speech.

Of these changes the most important are the dropping or modification of the old case-endings and of the stem-endings in compound words. Thus Early Celtic or British magos, a plain (stem mages-), gives Welsh ma, a place, Gaelic magh, a plain; vernos, alder, gives W. gwern, Ir. fearn, Scot.G. fearna. Verno-magos gives Fernmag, now Fearnmhagh, alder-plain. Gaelic still preserves inflection in a modified form, and distinct traces of the old declensions. Welsh has plural forms, but otherwise it has discarded inflection. It may be convenient to note here a few of the changes undergone by vowels and consonants.

• E.Celt. u is modified to i in Welsh, but remains u in Gaelic : dunon, a fort, W. din, G. dun.
• E.Celt. oi before a consonant gives u in Welsh, oi, oe in O.Ir., ao in Mod.G., O.Lat. oinos, Lat. unus one, W. fin, O.Ir. oen, Mod.G. aon.
• E.Celt. ei (usually written e) gives wy in Welsh before a consonant in Gaelic it becomes ia if followed originally by a broad vowel in the next syllable, but before a slender vowel it gives ei: letos grey, W. llwyd, G. liath, but its genitive leti gives G. leith.
• E.Celt. ou before a consonant (except s) gives u in W., ua in G. : boud-, victory (Boud-icca), W. budd, profit, Ir. buadh, triumph; Gaulish, Roud-ios, W. rhudd, G. ruadh, red.
• Initial s before a vowel gives h in Welsh usually, sometimes s ; in Gaelic it remains: W. hafal, G. samhail, Lat. similis, like; W. haf, summer, G. samh, but W. saith, seven, G. seacht, Lat. septem.
• Between vowels, in the body of a word, s becomes h, and then vanishes : Lat. esox, salmon (borrowed from Gaulish), Mid.W. ehawc, W. eog, Ir. eo, genitive iach.
• Initial sm- sn-, sl-, sr-, remain in Gaelic; in Welsh they become m-, n-, ll-, rh-, respectively: G. smear, marrow, W. mer; G. sleamhain, slippery, W. llyfn; G. sruth, stream, W. rhwd.
• Before r or l, st remains in Welsh ; in Gaelic it becomes s (as always) : W. ystrad, strath, G. srath ; W. ystlys, side, G. slios. 
• -lm- and -rm- remain in Gaelic ; in Welsh the m becomes f or w : Gaul. kourmi, G. cuirm, W. cwrf, cwrw.
• Initial v gives gw in Welsh, f in Gaelic : vernos alder, W. gwern, Ir. fearn; Lat. vinum, wine, W. gwin, O.Ir. fin, G. fion.
• When stressed or following a stress, -ijos, ijon give -ydd in Welsh; -ija gives -edd; in Gaelic all yield -e: E.Celt. novios, W. newydd, O.Ir. nue, new.
• The consonants p, t, k, b, d, g, m become in Welsh between vowels, b, d, g, f (dd), f, respectively: Caratacos W. Caradawg; Cunotamos, W. Cyndaf. This is called the soft mutation, otherwise lenition. 
• In Gaelic these consonants between vowels become aspirated : Caratacos, Ir. Carthach; aspiration is also called lenition. 
• In the body of a word, between vowels, soft or lenited g came to vanish in Welsh: Lat. legion-; Caer-leon. 
• Under the nasal mutation in Welsh, initial b, d, g become m, nn (n), ng, respectively; the tenues (c, t, p) become mediae (g, d, b) : in Bangor becomes ym Mangor. The corresponding change in Irish is called eclipsis : in Breatnaibh becomes i mBreatnaibh, pronounced i Mreatnaibh. Eclipsis has long been dropped in Scottish Gaelic, but the place-names show many cases of its former influence. 
• In Welsh early pp (British or Latin) gives ff ; tt gives th ; cc (kk) gives ch ; in Gaelic they give p, t, c (k), respectively : Britton-es, W. Brython, G. Breatan ; Lat. peccat-um, sin, W. pechod, G. peacadh.
• British or Latin act, oct, uct, ect, ict give respectively in W. aeth, oeth, wyth, eith (aith), ith. In G. the ct in each case becomes cht (Scot.G. chd) : W. caeth, Ir. cacht, slave; W. noeth, Ir. nocht ; W. wyth, Ir. ocht, Lat. octo ; W. rhaith, Ir. reacht, Lat. rect-um ; W. rhith, O.Ir. richt, G. riocht, riochd, form.
• E.Celt. ks, Lat. x give in Welsh is, in Gaelic s : laxus, W. llaes, G. las; pexa, a tunic, W. peis; coxa (koksa); W. coes, Ir. cos, Sc.G. cas, a foot; Saxo, W. Sais; Saxones, W. Saeson, Ir. Sasan-ach, an Englishman.

Long before the Romans actually entered North Britain the country was not wholly unknown by report. Albion, the ancient name of Great Britain as a whole, appears to go back to Himilco the Carthaginian, who explored the coasts of the North Sea about B.C. 500. Nearly two hundred years later (B.C. 320) came the famous expedition of Pytheas, organized by the traders of Massilia, to the same parts, and though Pytheas’ own account of his voyages is lost, fragments of it have been preserved. Pytheas had mentioned Thule. It was six days’ sail north of Britain, near the frozen sea, and the region about it was neither firm land nor sea nor air, but a mixture of all three resembling a jellyfish in consistency. Strabo, referring to this description, calls Pytheas an utter liar ; as for himself, he does not know whether Thule is an island or whether the region near it is habitable. Orcas, first mentioned by Diodorus as one of the three chief capes of Britain, is also from Pytheas; the other capes are Belerion and Cantion, Land’s End and South Foreland. The Roman geographer Mela (fl. A.D. 45) places Thule off the coast of the Belcae, ‘ a Scythian tribe.’ He is the first to mention the Orcades which, he says, number thirty, all close together; and as the number of inhabited islands in the group is now twenty-nine, it would appear that Mela wrote on good authority. The poet Lucan and his contemporaries (A.D. 39-65) have heard of the Caledonian Britons. Pliny (A.D. 23-79) names as sources of his information Pytheas, Timaeus (C. B.C. 352-256), and Isidorus of Charax, who was probably an elder contemporary of his own; there were others also whom he does not name. He states that there are forty Orcades, thirty Hebudes, seven Acmodae. He also mentions Mona, now Anglesey, between Britannia and Hibernia; Monapia, now Man; Riginia, equated with Rechrann or Rathlin; Vectis, the Isle of Wight; Silumnus; Andros or Adros, perhaps Ireland’s Eye; Dumna, the Long Island; and he has heard of Caledonia Silva, the Caledonian Forest. Such are the indications of the knowledge of North Britain possessed by the Romans before Agricola’s campaigns (A.D. 80-85). It relates chiefly to islands, and it is just the sort of information that might be got from seafarers who knew little about the interior. Probably most of it is referable ultimately to Pytheas.

Agricola’s campaigns form a distinct epoch, and it is unfortunate for us that Tacitus, his son-in-law and biographer, did not include in his Life of Agricola a systematic account of the. country and tribes among which his father-in-law operated, as he might so easily have done. From Tacitus we hear for the first time of the rivers Clota, the Clyde, Bodotria, the Forth, Tanaus or Taus, the Tay. The part north of Forth and Clyde is Caledonia ; its inhabitants are Britanni. He names only one tribe, the Boresti, but he implies the existence of other tribes, and gives the important information that they joined together under one leader to make common cause against the Romans. The champion of liberty – the first native of Scotland whose name appears on record-was Calgacus, ‘Swordsman,’ the most distinguished among all the chiefs for courage and for lineage. Historians have done him scant justice; he was of the type and race of Vercingetorix, the hero of Alesia, and, one might add, of Wallace; but though they are both commemorated by statues, he is not. The position of Mons Graupius, where he gave battle to the invaders, is still uncertain. Agricola showed his desire for further knowledge of the North by ordering his fleet to sail round the north coast. Three results of this cruise are claimed by Tacitus : Britain was proved to be an island; the Orcades, hitherto unknown, were discovered and subdued; the mysterious Thule, their northmost goal, was seen in the distance. The first of these results would be attained by rounding the north coast and sailing southward along the west coast to a point already known, such as the Firth of Clyde. As to the Orkneys, they were known by report, as we have seen, long before Agricola’s time, as Tacitus was doubtless well aware. What he meant was, we may suppose, that the Romans had now for the first time direct and accurate knowledge of these islands. By Thule he means Shetland. The position of the Trucculensis Portus, the port from which the fleet set out and to which it returned, cannot be settled ; but it must have been Montrose or some place either on the Firth of Forth or on the Firth of Tay. There can be no doubt that the voyage brought much new information about the North and West.

In the first half of the second century the famous mathematician, astronomer, and geographer, Claudius Ptolemy of Alexandria, embodied in his great Introduction to Geography the facts relating to North Britain as known in his time. He fixes his places by latitude and longitude, and following Marinus of Tyre, his older contemporary, he takes as his furthest north fixed point Thule, whose position had been fixed by Agricola’s survey. Ptolemy’s measurements of latitude and longitude show that he turned all Britain north of Solway and Tyne through a right angle : his furthest north point is the Mull of Galloway ; he makes the west coast face north, the north coast face east, and the east coast face south. Apart from this extraordinary error, which I am quite incompetent to discuss and which really does not concern our present purpose, the outline of the map constructed from the data which Ptolemy supplies is very creditable, and we shall see reason to believe that his names of tribes and places deserve great respect. He records and locates in what is now Scotland 16 or 18 tribes, 17 rivers, 16 towns, 10 islands, 7 capes, 3 bays, and 4 other names. Here is a great advance in method and in knowledge of detail. When, however, it comes to fixing the position of these on a modern map, the matter is one of much difficulty. The difficulty is least in the case of names that still survive, and greatest in the case of inhabited sites or ‘towns.’

Latin and Greek writers after Ptolemy’s time give little topographical information bearing on our subject. Dio Cassius’ contemporary account of the doings of the Emperor Severus in Scotland in the beginning of the third century is lost; but from the epitome of his history by Xiphilinus we learn that the two leading tribes then were the Caledonii and the Maeatae, and that the names of the others had practically been absorbed in these. ‘The Maeatae dwell close by the wall that divides the island into two parts, the Caledonii beyond them.’ . The reference here is probably to Hadrian’s Wall, between Tyne and Solway; this would put the Maeatae south of Forth, between the Walls.

The orator Eumenius in A.D. 297 speaks of the Britons of the province as accustomed to Picti and Hiberni (Picts and Irish) as enemies. In A.D. 310 another orator says: ‘I do not mention the woods and marshes of the Caledonians, the Picts, and others,’ or, according to another reading, ‘of the Caledonians and other Picts.’ In or about A.D. 364, the Picts divided into two tribes (gentes), the Dicalydones and the Verturiones, and also the Atecotti, a warlike nation, and the Scotti, ranged far and wide (in the Roman province) and made great ravaging.’ The Scotti were, of course, the Irish ; the Atecotti are styled by Jerome ‘a British tribe ‘ (gentem Britannicam [This does not exclude the possibility of the Atecotti having been Irish. Professor John MacNeill says, ‘The names Scotti and Atecotti … are probably of a general application, not designative of special groups.’Early Irish Population Groups, § 3.]), – but nothing certain is known as to their position. It is important to observe that in the fourth century the Caledonians have come to be a division of the Picts, and are not heard of subsequently. The inference is that that powerful tribe, which held the hegemony at Mons Graupius and after whom the North was called Caledonia, had for some reason lost their position of leadership, and that the Picts, who are first mentioned in A.D. 297, had taken their place. Thereafter the North came to be called Pictland (Pictavia), till the hegemony passed from them to the Scots. Thus we have the succession – Caledonia, Pictavia, Scotland.

William J. Watson “The History of the Celtic Place-Names of Scotland” 
(Edinburgh and London, 1926. Reprinted 1993 by Birlinn Limited, 13 Rosneath Street, Edinburgh, ). ISBN 1 874744 06 8.